Engineers must consider the breadths of male heads when designing helmets. The company researchers have determined that the population of potential clientele have head breadths that are Normally distributed with a mean of 6.5 inches and a standard deviation of 1.2 inches. According to the 68-95-99.7 rule, we expect 95% of head breadths to be:___________.

Answers

Answer 1

Answer:

"According to the 68-95-99.7 rule, we expect 95% [95.45%] of head breadths to be" between 4.1 inches and 8.9 inches.

Step-by-step explanation:

According to the 68-95-99.7 rule, approximately:

68% (more precisely, 68.27%) of the data from the normal distribution lie one standard deviation, [tex] \\ \sigma[/tex], above and below the population mean, [tex] \\ \mu[/tex].95% (more precisely, 95.45%) of the data lie two standard deviations, [tex] \\ 2\sigma[/tex], above and below the population mean, [tex] \\ \mu[/tex], and finally,99.7 (or more precisely, 99.73%) of the data lie three standard deviations, [tex] \\ 3\sigma[/tex], above and below the population mean, [tex] \\ \mu[/tex].

Then, if we have--from the question--that:

The random variable is head breadths.This variable follows a normal distribution.The population's mean for this distribution is [tex] \\ \mu = 6.5[/tex] inches.The population's standard deviation is [tex] \\ \sigma =1.2[/tex] inches.

We have to remember that two parameters characterize a normal distribution: the population's mean and the population's standard deviation. So, mathematically, the distribution we have from question is [tex] \\ N(6.5, 1.2)[/tex].

For 95% (95.45%) of the head breadths, we expect that they are two standard deviations below and above the population's mean.

For solving this, we need to use the cumulative standard normal distribution (in case we need to find probabilities) and also use standardized values or z-scores:

[tex] \\ z = \frac{x - \mu}{\sigma}[/tex] [1]

A z-score "tells us" the distance from the mean in standard deviations units. If the z-score is positive, it is above the mean. If it is negative, it is below the mean.

Since 95% (95.45%) of the head breadths are two standard deviations (above and below the mean), we have (using [1]):

[tex] \\ \pm2 = \frac{x - \mu}{\sigma}[/tex]

But we already know that [tex] \\ \mu=6.5[/tex] inches and [tex] \\ \sigma=1.2[/tex] inches.

Thus (without using units) for values above the population's mean:

[tex] \\ 2 = \frac{x - 6.5}{1.2}[/tex]

Solving the equation for x, we multiply by 1.2 at each side of [1] :

[tex] \\ 2 * 1.2 = \frac{x - 6.5}{1.2} * 1.2[/tex]

[tex] \\ 2 * 1.2 = (x - 6.5)\frac{1.2}{1.2}[/tex]

[tex] \\ 2 * 1.2 = (x - 6.5)\frac{1.2}{1.2}[/tex]

[tex] \\ 2 * 1.2 = (x - 6.5)*1[/tex]

[tex] \\ 2 * 1.2 = x - 6.5[/tex]

Adding 6.5 at each side of the previous equation:

[tex] \\ (2 * 1.2) + 6.5 = x - 6.5 + 6.5[/tex]

[tex] \\ (2 * 1.2) + 6.5 = x + 0[/tex]

[tex] \\ (2 * 1.2) + 6.5 = x[/tex]

Therefore, the raw value, x, in the distribution that is two standard deviations above the population's mean is:

[tex] \\ x = (2 * 1.2) + 6.5[/tex]

[tex] \\ x = 2.4 + 6.5[/tex]

[tex] \\ x = 8.9[/tex] inches.

For two standard deviations below the mean, we proceed in the same way:

[tex] \\ -2 = \frac{x - 6.5}{1.2}[/tex]

[tex] \\ -2*1.2 = x - 6.5[/tex]

[tex] \\ (-2*1.2) + 6.5 = x[/tex]

[tex] \\ x = (-2*1.2) + 6.5[/tex]

[tex] \\ x = -2.4 + 6.5[/tex]

[tex] \\ x = 4.1[/tex] inches

Therefore, "according to the 68-95-99.7 rule, we expect 95% [95.45%] of head breadths to be" between 4.1 inches and 8.9 inches.

The graph below shows these values, and the shaded area represents 95% of the data, or, to be more precise, 95.45% (0.954499).  

Engineers Must Consider The Breadths Of Male Heads When Designing Helmets. The Company Researchers Have

Related Questions

find the circumference of the circle use 3.14 for pi when the radius is 13 cm

Answers

Answer:

C =81.64 cm

Step-by-step explanation:

The circumference of a circle is given by

C = 2*pi*r

C = 2 * 3.14 * 13

C =81.64 cm

_______________________________

Radius(r)=13 cm

Circumference of circle=?

Now,

Circumference of circle=2 pi r

=2*3.14*13

=81.64 cm

Hope it helps..

Good luck on your assignment

________________________________

Write the ratio 70:80 in its simplest form

Answers

Answer:

7/8!

Step-by-step explanation:

They both can be divided by 10, so do just that. Then you are left with 7/8 which cannot be simplified.

The ratio 70:80 in its simplest form is equal to 7:8.

To simplify the ratio 70:80, we need to find the greatest common divisor (GCD) of the two numbers and then divide both numbers by the GCD.

Step 1: Find the GCD of 70 and 80:

The factors of 70 are 1, 2, 5, 7, 10, 14, 35, and 70.

The factors of 80 are 1, 2, 4, 5, 8, 10, 16, 20, 40, and 80.

The common factors of 70 and 80 are 1, 2, 5, and 10. The greatest common divisor (GCD) is 10.

Step 2: Divide both numbers by the GCD (10):

70 ÷ 10 = 7,

80 ÷ 10 = 8.

In summary, the ratio 70:80 can be simplified by dividing both numbers by their greatest common divisor (GCD), which is 10. After simplification, the ratio becomes 7:8. Simplifying ratios involves dividing both parts of the ratio by the greatest common factor to express the ratio in its simplest and most concise form.

This makes it easier to understand and work with the relationship between the quantities being compared. In this case, the simplified ratio tells us that for every 7 units of the first quantity, there are 8 units of the second quantity.

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fand f are functions.
If f(4) = 2 then f'(2) = ?

Answers

Answer:

4

Step-by-step explanation:

[tex] \because \: f(4) = 2 \\ \therefore \: {f}^{ - 1} (f(4)) = {f}^{ - 1} (2) \\ \therefore \: 4 = {f}^{ - 1} (2) \\ \huge \red{ \boxed{{f}^{ - 1} (2) = 4}}[/tex]

Answer:

4 four

Step-by-step explanation:

hope it helps you

If a tank holds 4500 gallons of water, which drains from the bottom of the tank in 50 minutes, then Toricelli's Law gives the volume V of water remaining in the tank after t minutes as V = 4500 1 − 1 50 t 2 0≤ t ≤ 50. Find the rate at which water is draining from the tank after the following amounts of time.a) 5 min 855 x gal/min b) 10 min 160 x gal/min c) 20 min 120 x gal/min d) 50 min gal/min

Answers

Answer:

a) at 5 minutes: 162 gal/min

b) at 10 minutes:  144 gal/min

c) at 20 minutes:  108 gal/min

d) at 50 minutes: 0 gal/min

Step-by-step explanation:

Considering the formula given by the volume of water remaining in the tank:

[tex]V(t)=4500\,(1-\frac{1}{50} \,t)^2[/tex]

we can find the rate of water draining from the tank, (that is change in volume divided elapsed time) with the derivative of the function at the different times. Notice that this function has a decaying curvature (see attached image) of volume as a function of time, and the idea is therefore to find the slope of the tangent line at the different requested times.

So we first calculate the derivative of this function at any time 't":

[tex]V(t)=4500\,(1-\frac{1}{50} \,t)^2\\V'(t)=9000\,(1-\frac{1}{50} \,t)\,(-\frac{1}{50})\\V'(t)=-180(1-\frac{1}{50} \,t)\\V'(t)=-180+3.6\,t[/tex]

And now we estimate this derivative at the different requested points for time values:

a) at 5 minutes:  [tex]V'(5)=-180+3.6\,(5) = -162\,\,gal/min[/tex]

b) at 10 minutes:   [tex]V'(10)=-180+3.6\,(10) = -144\,\,gal/min[/tex]

c) at 20 minutes:   [tex]V'(20)=-180+3.6\,(20) = -108\,\,gal/min[/tex]

d) at 50 minutes:  [tex]V'(50)=-180+3.6\,(50) = 0\,\,gal/min[/tex]

All the negative signs preceding indicate that the remaining volume in the tank is reducing as time goes by, so the volume at which the water is draining is actually the absolute value of those numbers.

A hospital claims that the proportion, , of full-term babies born in their hospital that weigh more than pounds is . In a random sample of babies born in this hospital, weighed over pounds. Is there enough evidence to reject the hospital's claim at the

Answers

Complete question is:

A hospital claims that the proportion, p, of full-term babies born in their hospital that weigh more than 7 pounds is 36%. In a random sample of 170 babies born in this hospital, 56 weighed over 7 pounds. Is there enough evidence to reject the hospital's claim at the level of significance?

Answer:

Yes, there is enough evidence to reject the claim.

Step-by-step explanation:

We are given;

n = 170

x = 56

So, will use one sample proportion test to solve this.

p^ = x/n

p^ = 56/170

p^ = 0.3294

Since the proportion, p, of full-term babies born in their hospital that weigh more than 7 pounds is 36%.

Thus;

Null Hypothesis H0: p ≠ 0.36

Alternative Hypothesis Ha: p = 0.36

Formula for test statistic = (p^ - p)/√(p(1 - p)/n)

This gives;

Test statistic = (0.3294 - 0.36)/√(0.36(1 - 0.36)/170)

Test statistic = -0.8311

From z-table and online z-calculator, the p - value is 0.203.

level of significance is; α = 0.05

Now, Since the p value < α, we reject the null hypothesis .

Thus, the claim is true

if jm = 5x - 8 and lm = 2x - 6, which expression represents jl

Answers

Answer:

7x -14 = jl

Step-by-step explanation:

Assuming a straight line

jm+ ml = jl

5x-8 + 2x-6 = jl

Combine like terms

7x -14 = jl

7x-14=jl assuming a straight line

The manufacturer of a smart watch claims that individuals who pay attention to how many steps they take per day will inadvertently take more steps per day than individuals who pay no attention to how many steps they take per day. To investigate this claim, the manufacturer conducts a study to estimate the difference in the mean number of steps taken by those that pay attention to how many steps they take per day and those that do not. To do so, 40 volunteers are recruited. Half of the volunteers are randomly assigned to receive a smart watch and are taught how to use it to track their steps. The other half of the volunteers are given a wristband to wear, but are not informed that the wristband is tracking their steps. The volunteers are monitored for 30 days. The mean and standard deviation of the number of steps taken per day are computed for each group. Here are the data:
Payti
Do not pay itin 01 0 10 20 87 64 82 350
Which of the following is a 99% confidence interval for the difference in the mean number of steps taken by all people like these that do and do not pay attention to the number of steps they take per day using df - 192
(A) 1596 + 2.861/15802 + 23502
(B) 1596 +2.861, 15.302 – 23502
(C) 1596 +2.576,15802 + 23502
(D) 1596 + 2.576 ( 15802 + 23502) °
(E) 1596 + 2.576 ( 15892 – 23502)

Answers

Here is the correct question.

The manufacturer of a smart watch claims that individuals who pay attention to how many steps they take per day will inadvertently take more steps per day than individuals who pay no attention to how many steps they take per day. To investigate this claim, the manufacturer conducts a study to estimate the difference in the mean number of steps taken by those that pay attention to how many steps they take per day and those that do not. To do so, 40 volunteers are recruited. Half of the volunteers are randomly assigned to receive a smart watch and are taught how to use it to track their steps. The other half of the volunteers are given a wristband to wear, but are not informed that the wristband is tracking their steps. The volunteers are monitored for 30 days. The mean and standard deviation of the number of steps taken per day are computed for each group. Here are the data:

                                           [tex]n[/tex]                     [tex]\bar x[/tex]                  [tex]S_x[/tex]

Pay attention                    20                 10,244            1,580

Do not pay attention        20                 8.,648            2,350

Which of the following is a 99% confidence interval for the difference in the mean number of steps taken by all people like these that do and do not pay attention to the number of steps they take per day using df - 19 ?

[tex](A) \ 1596 \ \pm 2.861 \sqrt{ \dfrac{1580^2}{20} + \dfrac{2350^2}{20}} \\ \\ \\ (B) \ 1596 \ \pm 2.861 \sqrt{ \dfrac{1580^2}{20} - \dfrac{2350^2}{20}} \\ \\ \\ (C) \ 1596 \pm 2.576 \sqrt{ \dfrac{1580^2}{20} + \dfrac{2350^2}{20}} \\ \\ \\ (D) 1596 \pm 2.576 ( \dfrac{1580^2}{\sqrt{20}} + \dfrac{2350^2}{\sqrt{20}}) \\ \\ \\ (E) 1596 \pm 2.576 ( \dfrac{1580^2}{\sqrt{20}} - \dfrac{2350^2}{\sqrt{20}})[/tex]

Answer:

[tex]\mathbf{(A) \ 1596 \ \pm 2.861 \sqrt{ \dfrac{1580^2}{20} + \dfrac{2350^2}{20}}}[/tex]

Step-by-step explanation:

Given that :

significance level [tex]\alpha = \mathbf{0.01}[/tex]

From the Given data;

Using Excel with the function : TINV(0.01,19);

Critical value t* = 2.861

The margin of error can now be represented by the illustration:

Margin of error = [tex]t^* \sqrt{ \dfrac {s_1 ^2}{n_1} + \dfrac {s_2 ^2}{n_2}[/tex]

Lower Limit =  [tex](\bar x_1 - \bar x_2)- (Margin \ of \ error)[/tex]

Upper Limit =  [tex](\bar x_1 - \bar x_2)+ (Margin \ of \ error)[/tex]

Thus; the confidence interval for the difference in the mean number of steps taken by all people like these that do and do not pay attention to the number of steps they take per day using df - 19 is:

[tex]\mathbf{(A) \ 1596 \ \pm 2.861 \sqrt{ \dfrac{1580^2}{20} + \dfrac{2350^2}{20}}}[/tex]

How long is a average teen suppose to be

Answers

Answer:

The way adolescents spend their time can strongly influence their health later in life. For youth to maintain a healthy future, they need plenty of sleep; good nutrition; regular exercise; and time to form relationships with family, friends, and caring adults. Additionally, the time adolescents spend in school and in after-school activities with peers and adults can advance healthy academic, emotional, social, and physical development. The amount of time they spend on screens and in social media may also influence adolescents’ overall well-being.

The American Time Use Survey, collected by the U.S. Bureau of Labor Statistics, contains detailed information about how individuals ages 15 and older use their time and provides a picture of a typical weekday and weekend day for a high school teen during the school year. Here we specifically analyze how adolescents ages 15-19 who are enrolled in high school spend their time.

Step-by-step explanation:

3km 5hm multiplied by 15 equals what

Answers

Answer: 525

Step-by-step explanation:

3 km =30 hm

35hm*15=525

Find the median of the data in the dot plot below.

Answers

The value of the median is 25 from the dot plot because the middle value is 25 on the dot plot,

What is the median?

A median is a middle number in a series of numbers that have been arranged to lift, and it might be more informative of the set of data than the average. When there are extremes in the sequences that might affect the average of the numbers, the median is sometimes employed instead of the mean.

We have a dot plot shown in the picture.

As we can see in the dot plot there are a total of 9 dots.

4 dots left side and 4 dots right side.

One dot is left which is pointing to the value 25 at the number line.

Thus, the value of the median is 25 from the dot plot because the middle value is 25 on the dot plot,

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Steve wants to use his 18% employee discount to buy a video game that has a regular price of $69.99. A 6.5% sales tax is applied to the discounted price. How much will he pay for the game, including sales tax?

Answers

Answer:

$61.12

Step-by-step explanation:

Price of the Video game = $69.99

Discount = 18%

Discount price = 18% of $69.99

                         = $69.99*18/100

                         = $12.6

Price after Discount = Price - Discount price

                                  = $69.99 - $12.6

                                  = $57.39

Sales tax = 6.5% applied to the discounted price

                = 6.5% of $57.39

sales tax in dollars = $57.39 * 6.5/100

                               = $3.73

The amount he pays for the game = $57.39 + $3.73

                                                          = $61.12

ADDITIONAL 100 POINTS PLS HELP ASAP follow up question ( first question on log )

Answers

As the cube gets bigger, the volume increases much more rapidly than the surface area, because the volume increases as the cube of the linear dimension, but the surface area increases as the square. This relationship applies, not just to cubes, but to spheres and any other fixed shape. Similarly when length is tripled (x = 3) surface area is increased ninefold (32 = 9) and volume is increased twenty-sevenfold (33 = 27). The increase in volume is always greater than the increase in surface area.
...
Variables:
S surface area (units squared)
V volume (units cubed)
l length (units)
r radius (units)

Answer:

Hello!

I believe this is what you are looking for:

x=3

33=27

32=9

S=Surface area

V=Volume

L=Length

R=Radius

I hope this helped.  If not, please let me know.  I will try my best again. :)

Step-by-step explanation:

Environmental Protection Agency standards require that the amount of lead in drinking water be less than 15 ppb. Twelve samples of water from a particular source have the following concentrations, in ppb. 11.4 13.9 11.2 14.5 15.2 8.1 12.4 8.6 10.5 17.1 9.8 15.9 A hypothesis test will be performed to determine whether the water from this source meets the EPA standard.

Required:
a. State the appropriate null and alternate hypotheses.
b. Compute the P-value.
c. Can you conclude that the water from this source meets the EPA standard? Explain.

Answers

Answer:

Step-by-step explanation:

Mean = (11.4 + 13.9 + 11.2 + 14.5 + 15.2 + 8.1 + 12.4 + 8.6 + 10.5 + 17.1 + 9.8 + 15.9)/12 = 12.4

Standard deviation = √(summation(x - mean)²/n

n = 12

Summation(x - mean)² = (11.4 - 12.4)^2 + (13.9 - 12.4)^2 + (11.2 - 12.4)^2+ (14.5 - 12.4)^2 + (15.2 - 12.4)^2 + (8.1 - 12.4)^2 + (12.4 - 12.4)^2 + (8.6 - 12.4)^2 + (10.5 - 12.4)^2 + (17.1 - 12.4)^2 + (9.8 - 12.4)^2 + (15.1 - 12.4)^2 = 89.62

Standard deviation = √(89.62/13) = 2.7

We would set up the hypothesis test. This is a test of a single population mean since we are dealing with mean

a) For the null hypothesis,

µ ≤ 15

For the alternative hypothesis,

µ > 15

This is a right tailed test

b) Since the number of samples is small and no population standard deviation is given, the distribution is a student's t.

Since n = 12,

Degrees of freedom, df = n - 1 = 12 - 1 = 11

t = (x - µ)/(s/√n)

Where

x = sample mean = 12.4

µ = population mean = 15

s = samples standard deviation = 2.7

t = (12.4 - 15)/(2.7/√12) = - 3.34

We would determine the p value using the t test calculator. It becomes

p = 0.0034

c) Assuming level of significance = 0.05.

Since alpha, 0.05 > than the p value, 0.0034, then we would reject the null hypothesis. Therefore, At a 5% level of significance, we can conclude that the water from this source does meets the EPA standard. They are higher than 15ppb

Using the t-distribution, we have that:

a)

The null hypothesis is: [tex]H_0: \mu \geq 15[/tex]

The alternative hypothesis is: [tex]H_1: \mu < 15[/tex]

b) The p-value is of 0.0051.

c) Since the p-value is of 0.0051, which is less than the standard significance level of 0.0051, it can be concluded that the mean is less than 15 ppb, and thus, this source meets the EPA standard.

Item a:

At the null hypothesis, it is tested if the mean is of at least 15 ppb, that is:

[tex]H_0: \mu \geq 15[/tex]

At the alternative hypothesis, it is tested if the mean is of less than 15 ppb, that is:

[tex]H_1: \mu < 15[/tex]

Item b:

We have the standard deviation for the sample, thus, the t-distribution is used. The test statistic is given by:

[tex]t = \frac{\overline{x} - \mu}{\frac{s}{\sqrt{n}}}[/tex]

The parameters are:

[tex]\overline{x}[/tex] is the sample mean. [tex]\mu[/tex] is the value tested at the null hypothesis. s is the standard deviation of the sample. n is the sample size.

In this problem, we have that [tex]\mu = 15, n = 12[/tex]. Additionally, using a calculator, the other parameters are: [tex]\overline{x} = 12.38, s = 2.93[/tex]

Hence, the value of the test statistic is:

[tex]t = \frac{\overline{x} - \mu}{\frac{s}{\sqrt{n}}}[/tex]

[tex]t = \frac{12.38 - 15}{\frac{2.93}{\sqrt{12}}}[/tex]

[tex]t = -3.1[/tex]

The p-value is found using a left-tailed test, as we are testing if the mean is less than a value, with t = -3.1 and 12 - 1 = 11 df.

Using a calculator, this p-value is of 0.0051.

Item c:

Since the p-value is of 0.0051, which is less than the standard significance level of 0.0051, it can be concluded that the mean is less than 15 ppb, and thus, this source meets the EPA standard.

A similar problem is given at https://brainly.com/question/16194574

6
Cheryl had 160 stickers more than Gareth. If Cheryl gave 185 stickers
to Gareth, Gareth would have 3 times as many stickers as Cheryl
How many stickers did Gareth have at first?
165​

Answers

Answer:

260 stickers

Step-by-step explanation:

Let Gareth's stickers be x.

Hence Cheryl sticker is 160+x;

If Cheryl gave 185 stickers

to Gareth, it means:

Cheryl has at the moment;

160 + x - 185 = x - 25

At this time when Gareth receives 185 he now has:

x+ 185

Also when he receives x +185, he has 3 times Cherry's meaning:

x+185 =3(x-25)

x + 185 = 3x -75

185 + 75 = 3x-2x

260= x

x = 260.

Hence Gareth has 260 stickers

If the area of a triangle is 36 in.^2in. ​2 ​​ and the base is 9 in., what is the height of the triangle?

Answers

Answer:

Height = 8

Step-by-step explanation:

Area of a triangle = [tex]\frac{Base*Height}{2}[/tex]

Say the height = x

4.5x = 36

x = 8

The null and alternative hypotheses for a hypothesis test of the difference in two population means are: Alternative Hypothesis: p1 > p2 Null Hypothesis: Hi = uz Notice that the alternative hypothesis is a one-tailed test. Suppose proportions_ztest method from statsmodels is used to perform the test and the output is (3.25, 0.o43).
What is the P-value for this hypothesis test?
A. 0.00215
B. 0.0043
C. 3.25
D. -3.25

Answers

Answer:

B. 0.0043

Step-by-step explanation:

The null and alternative hypothesis of this one-tailed test are:

[tex]H_0: p_1-p_2=0\\\\H_a:p_1-p_2> 0[/tex]

The output of proportions_ztest method from statsmodels is a size-2 vector with the value of the test statistic and the P-value.

Then, if the output is (3.25, 0.0043), the P-value for this one-tailed test is 0.0043.

Mist (airborne droplets or aerosols) is generated when metal-removing fluids are used in machining operations to cool and lubricate the tool and work-piece. Mist generation is a concern to OSHA, which has recently lowered substantially the workplace standard. The article "Variables Affecting Mist Generation from Metal Removal Fluids" (Lubrication Engr., 2002: 10-17) gave the accompanying data on x = fluid flow velocity for a 5% soluble oil (cm/sec) and y = the extent of mist droplets having diameters smaller than some value:
x: 89 177 189 354 362 442 965
y: .40 .60 .48 .66 .61 .69 .99
a. Make a scatterplot of the data. By R.
b. What is the point estimate of the beta coefficient? (By R.) Interpret it.
c. What is s_e? (By R) Interpret it.
d. Estimate the true average change in mist associated with a 1 cm/sec increase in velocity, and do so in a way that conveys information about precision and reliability.
e. Suppose the fluid velocity is 250 cm/sec. Find the mean of the corresponding y in a way that conveys information about precision and reliability. Use 95% confidence level. Interpret the resulting interval. By hand, as in part d.
f. Suppose the fluid velocity for a specific fluid is 250 cm/sec. Predict the y for that specific fluid in a way that conveys information about precision and reliability. Use 95% prediction level. Interpret the resulting interval. By hand, as in part d.

Answers

Answer:

Step-by-step explanation:

a) image attached

b) Lets do the analysis in R , the complete R snippet is as follows

x<- c(89,177,189,354,362,442,965)

y<- c(.4,.6,.48,.66,.61,.69,.99)

# scatterplot

plot(x,y, col="red",pch=16)

# model

fit <- lm(y~x)

summary(fit)

#equation is

#y = 0.4041 + 0.0006211*X

# beta coeffiecients are

fit$coefficients

coef(summary(fit))[, "Std. Error"]

# confidence interval of slope

confint(fit, 'x', level=0.95)

The results are

> summary(fit)

Call:

lm(formula = y ~ x)

Residuals:

1 2 3 4 5 6 7

-0.05940 0.08595 -0.04151 0.03602 -0.01895 0.01136 -0.01346

Coefficients:

Estimate Std. Error t value Pr(>|t|)

(Intercept) 4.041e-01 3.459e-02 11.684 8.07e-05 ***

x 6.211e-04 7.579e-05 8.195 0.00044 ***

---

Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

Residual standard error: 0.05405 on 5 degrees of freedom

Multiple R-squared: 0.9307,   Adjusted R-squared: 0.9168 # model is able to capture 93% of the variation of the data

F-statistic: 67.15 on 1 and 5 DF, p-value: 0.0004403 , p value is less than 0.05 , hence model as a whole is significant

> fit$coefficients

(Intercept) x

0.4041237853 0.0006210758

> coef(summary(fit))[, "Std. Error"]

(Intercept) x

3.458905e-02 7.579156e-05

> confint(fit, 'x', level=0.95)

2.5 % 97.5 %

x 0.0004262474 0.0008159042

c)

> x=c(89,177,189,354,362,442,965)

> y=c(0.40,0.60,0.48,0.66,0.61,0.69,0.99)

>

> ### linear model

> model=lm(y~x)

> summary(model)

Call:

lm(formula = y ~ x)

Residuals:

1 2 3 4 5 6 7

-0.05940 0.08595 -0.04151 0.03602 -0.01895 0.01136 -0.01346

Coefficients:

Estimate Std. Error t value Pr(>|t|)    

(Intercept) 4.041e-01 3.459e-02 11.684 8.07e-05 ***

x 6.211e-04 7.579e-05 8.195 0.00044 ***

---

Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

Residual standard error: 0.05405 on 5 degrees of freedom

Multiple R-squared: 0.9307, Adjusted R-squared: 0.9168

F-statistic: 67.15 on 1 and 5 DF, p-value: 0.0004403

s_e is the Residual standard error from the model and its estimated value is 0.05405. s_e is the standard deviation of the model.  

d) 95% confidence interval

> confint(model, confidence=0.95)

2.5 % 97.5 %

(Intercept) 0.3152097913 0.4930377793

x 0.0004262474 0.0008159042

Comment: The estimated confidence interval of slope of x does not include zero. Hence, x has the significant effect on y at 0.05 level of significance.

 e)

> predict(model, newdata=data.frame(x=250), interval="confidence", level=0.95)

fit lwr upr

1 0.5593927 0.5020485 0.616737

f)

> predict.lm(model, newdata=data.frame(x=250), interval="prediction", level=0.95)

fit lwr upr

1 0.5593927 0.4090954 0.7096901

Suppose the labor force is 189 million of a possible 244 million working-age adults. The total number of unemployed is 15 million. What
is the standard unemployment rate?

Answers

Answer:

The standard unemployment rate is of 0.0794 = 7.94%.

Step-by-step explanation:

The standard unemployment rate, as a proportion, is the number of unemployed people divided by the size of the labor force.

In this question:

Labor force: 189 million

Number of unemployed people: 15 million

What is the standard unemployment rate?

15/189 = 0.0794

The standard unemployment rate is of 0.0794 = 7.94%.

Labrador Retriever weighs 48 kg after a diet and exercise program the dog weighs 43 kilograms to determine if this shows a percent increase or decrease and explain why what is the percent change of its weight a 10% B 11% C 110% D 111% please help.​

Answers

Answer:

percentage change in weight ≈ 10%

Step-by-step explanation:

The dog weighed 48 kg after a diet and after an exercise program the dog had a weight of 43 kg. This means the dog loss weight since the dog weight decreased from an initial value of 48 kg to 43 kg. The decrease in weight can be calculate as

decrease in weight = original weight - new weight

original weight  = 48 kg

new weight = 43 kg

decrease in weight = 48 - 43 = 5 kg

Since the weight decrease their will be a percentage decrease in weight.

% decrease = decrease in weight/original weight × 100

% decrease = 5/48 × 100

% decrease = 500/48

% decrease = 10. 42666666667

percentage change in weight ≈ 10%

A ball is thrown downward from the top of a 240​-foot building with an initial velocity of 20 feet per second. The height of the ball h in feet after t seconds is given by the equation h= -16t^2 - 20t + 240. How long after the ball is thrown will it strike the​ ground?

Answers

Answer:

3.29 s

Step-by-step explanation:

We are given that

Height of building=240

Initial velocity=20ft/s

The height of the ball  after t seconds is given by

[tex]h(t)=-16t^2-20t+240[/tex]

When the ball strike the ground then

h(t)=0

[tex]-16t^2-20t+240=0[/tex]

[tex]4t^2+5t-60=0[/tex]

Quadratic formula:

[tex]x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}[/tex]

Using the quadratic formula

[tex]t=\frac{-5\pm\sqrt{25+960}}{8}[/tex]

[tex]t=\frac{-5\pm\sqrt{985}}{8}[/tex]

[tex]t=\frac{-5+31.28}{8}=3.29 s[/tex]

[tex]t=\frac{-5-31.38}{8}=-4.5[/tex]

Time cannot be negative .Therefore,

t=3.29 s

A standardized​ exam's scores are normally distributed. In a recent​ year, the mean test score was 1521 and the standard deviation was 314. The test scores of four students selected at random are 1920​, 1290​, 2220​, and 1420. Find the​ z-scores that correspond to each value and determine whether any of the values are unusual

Answers

Answer:

A score of 1920 has a z-score of 1.27.

A score of 1290 has a z-score of -0.74.

A score of 2220 has a z-score of 2.23.

A score of 1420 has a z-score of -0.32.

The score of 2220 is more than two standard deviations from the mean, so it is unusual.

Step-by-step explanation:

When the distribution is normal, we use the z-score formula.

In a set with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the zscore of a measure X is given by:

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

If X is 2 or more standard deviations from the mean, it is considered unusual.

In this question, we have that:

[tex]\mu = 1521, \sigma = 314[/tex]

Score of 1920:

X = 1920. Then

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

[tex]Z = \frac{1920 - 1521}{314}[/tex]

[tex]Z = 1.27[/tex]

A score of 1920 has a z-score of 1.27.

Score of 1290:

X = 1290. Then

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

[tex]Z = \frac{1290 - 1521}{314}[/tex]

[tex]Z = -0.74[/tex]

A score of 1290 has a z-score of -0.74.

Score of 2220:

X = 1290. Then

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

[tex]Z = \frac{2220 - 1521}{314}[/tex]

[tex]Z = 2.23[/tex]

A score of 2220 has a z-score of 2.23.

Since it is more than 2 standard deviations of the mean, the score of 2220 is unusual.

Score of 1420:

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

[tex]Z = \frac{1420 - 1521}{314}[/tex]

[tex]Z = -0.32[/tex]

A score of 1420 has a z-score of -0.32.

What’s 148+383-163=?

Answers

Answer:

368

Step-by-step explanation:

Please help me explain your answer only answer if you are sure

Answers

Answer:

The answer of top prism is 262

and down prism is 478

The upper figure is triangular prism.

so, we use bh+2ls+lb formula

B=5

h=3

s=4

l=19

Now,

surface area of triangular prism = bh+2ls+lb

= 5×3+2×19×4+19×5

= 262

The down figure is rectangular prism.

so, we use 2lw+2lh+2hw

l=5

h=6

w=19

Now,

The area of rectangular prism = 2lw+2lh+2hw

= 2×5×19+2×19×6+2×5×6

= 478

Answer on top is prism 262

Which of the following functions is graphed below

Answers

Answer:

B

Step-by-step explanation:

Classify the following triangle .check all that apply

Answers

Answer:

Its right and scalene.

It has a right angle and all the sides are diferent.

Which expression is equivalent to 36 a minus 27?
9 (4 a minus 3)
3 (18 a minus 9)
9 (4 a minus 27)
3 (12 a minus 6)

Answers

Answer:

[tex]9(4a)-9(3)[/tex]

Step-by-step explanation:

[tex]36a-27[/tex]

[tex]9(4a)-9(3)[/tex]

[tex]9(4a-3)[/tex]

Answer:

it is 9(4a-3)

Step-by-step explanation:

If an exponential model was used to fit the data set below, which of the following would be the best prediction for the output of the model if the input was x=20?

Answers

Answer:

The equation is found to be: [tex]y = 50.6e^{0.16x}[/tex]

y(20) = 1241.34

Step-by-step explanation:

The given data is:

x:   3          7         11        14          17

y: 83      142      301     450      722

Now, we find sum summation values, relevant to the formula of exponential regression model, using calculator:

∑ ln y = 27.77305, ∑x ln y = 308.1494, ∑x = 52, ∑ x² = 664

and, n = no. of data points = 5

Now, we use formulae of exponential regression model to find out values of constant:

b = (n∑x lny - ∑x ∑ln y)/[n∑x² - (∑x)²]

b = [(5)(308.1494) - (52)(27.77305)]/[(5)(664) - (52)²]

b = 0.16

Now, for a;

a = (∑ln y - b∑x)/n

Therefore,

a = [(27.77305) - (0.16)(52)]/5

a = 3.9

For, α:

α = e^a = e^3.9

α = 50.6

So, the final equation of exponential regression model is given as:

[tex]y = \alpha e^{bx}\\ y = 50.6e^{0.16x}[/tex]

Now, we find value of y for x = 20:

y(20) = (50.6) e^(0.16*20)

y(20) = 1241.34

evaluate the formula of A=lw, for l=10.8 cm and w=2.5 cm​

Answers

Answer:

A = 27 cm²

Step-by-step explanation:

[tex]A = lw\\Where, l=10.8 cm , w = 2.5 cm\\[/tex]

Putting in the above formula

A = (10.8)(2.5)

A = 27 cm²

Find the quotient
-99 over -11

Answers

Answer:

the quotient is 9 because a negative divided by a negative is a positive

The answer is "A"
"negative number divide with negative number result in positive number"​
-99/-11=9

In the circle below, CD is a diameter. If AE=10, CE=4, and AB=16, what is
the length of the radius of the circle?
Please Help ASAP

Answers

Answer:

(D)9.5 Units

Step-by-step explanation:

We have two chords CD and AB intersecting at E.

Using the theorem of intersecting chords

AE X EB =CE X ED

AE=10CE=4AB=16

AB=AE+EB

16=10+EB

EB=16-10=6

Therefore:

AE X EB =CE X ED

10 X 6 = 4 X ED

ED =60/4 =15

Therefore:

CD=CE+ED

=4+15

CD=19

Recall that CD is a diameter of the circle and;

Radius =Diameter/2

Therefore, radius of the circle =19/2 =9.5 Units

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