In a sample of 80 light bulbs, the mean lifetime was 1217 hours with a standard deviation of 52 hours. a. Find the 95% confidence interval for the mean lifetime of this type of bulb. Justify the reason you chose the distribution used to construct the confidence interval. b. How many light bulbs must be sampled so that a 95% confidence interval will specify the mean lifetime to within + 8 hours?
Complete Question
In a sample of 80 light bulbs, the mean lifetime was 1217 hours with a standard deviation of 52 hours. a. Find the 95% confidence interval for the mean lifetime of this type of bulb. Justify the reason you chose the distribution used to construct the confidence interval. b. How many light bulbs must be sampled so that a 95% confidence interval will specify the mean lifetime to within [tex]\pm 8 \ hours[/tex]?
Answer:
a
[tex]1206 < \mu < 1228 [/tex]
The reason why a normal distribution was chosen is because the sample size is large enough that is [tex]n > 30[/tex]
b
[tex]n =162 [/tex]
Step-by-step explanation:
From the question we are told that
The sample size is n = 80
The sample mean is [tex]\= x = 1217[/tex]
The standard deviation is [tex]\sigma = 52[/tex]
From the question we are told the confidence level is 95% , hence the level of significance is
[tex]\alpha = (100 - 95 ) \%[/tex]
=> [tex]\alpha = 0.05[/tex]
Generally from the normal distribution table the critical value of is
[tex]Z_{\frac{\alpha }{2} } = 1.96[/tex]
Generally the margin of error is mathematically represented as
[tex]E = Z_{\frac{\alpha }{2} } * \frac{\sigma }{\sqrt{n} }[/tex]
=> [tex]E = 1.96 * \frac{ 52}{\sqrt{80} }[/tex]
=> [tex]E = 11.395 [/tex]
Generally 95% confidence interval is mathematically represented as
[tex]\= x -E < \mu < \=x +E[/tex]
=> [tex]1217 -11.395 < \mu < 1217 + 11.395[/tex]
=> [tex]1206 < \mu < 1228 [/tex]
Generally the sample size is mathematically represented as
[tex]n = [\frac{Z_{\frac{\alpha }{2} } * \sigma }{E} ] ^2[/tex]
Here E = 8
=> [tex]n = [\frac{1.96 * 52 }{8} ] ^2[/tex]
=> [tex]n =162 [/tex]
Find the solution of the second-order linear differential equation that satisfies the given initial conditions. y'' + 6y' + 9y = 0 y(0) = 0 y'(0) = 1
Answer:
The solution of this differential system is [tex]y(x) = x\cdot e^{3\cdot x}[/tex].
Step-by-step explanation:
This second-order differential equation is homogeneous and linear of the form:
[tex]y'' + p\cdot y' +q\cdot y = 0[/tex] (1)
Where:
[tex]p[/tex] - First-order constant coefficient, dimensionless.
[tex]q[/tex] - Zero-order constant coefficient, dimensionless.
Whose characteristic polynomial is:
[tex]\lambda^{2}+p\cdot \lambda + q = 0[/tex] (2)
Where [tex]\lambda[/tex] contains the roots associated with the solution of the differential equation.
If we know that [tex]p = 6[/tex] and [tex]q = 9[/tex], the roots of the characteristic equation are, respectively:
[tex]\lambda^{2}+6\cdot \lambda + 9 = 0[/tex]
[tex](\lambda +3)\cdot (\lambda + 3) = 0[/tex]
Which means that [tex]\lambda_{1} = \lambda_{2} = 3[/tex] and the solution of the differential equation is of the form:
[tex]y(x) = e^{3\cdot x}\cdot (c_{1}+c_{2}\cdot x)[/tex] (3)
Where [tex]c_{1}[/tex] and [tex]c_{2}[/tex] are integration constants.
The first derivative of the equation above is:
[tex]y'(x) = 3\cdot e^{3\cdot x}\cdot (c_{1}+c_{2}\cdot x)+c_{2}\cdot e^{3\cdot x}[/tex] (4)
Now, if we get that [tex]y(0) = 0[/tex] and [tex]y'(0) = 1[/tex], then the system of equations to the solved is:
[tex]c_{1} = 0[/tex] (3b)
[tex]c_{1}+c_{2} = 1[/tex] (4b)
The solution of this system is: [tex]c_{1} = 0[/tex], [tex]c_{2} = 1[/tex]. Therefore, the solution of this differential system is [tex]y(x) = x\cdot e^{3\cdot x}[/tex].
Identify the coefficient in 0.50(m)-0.20(g)+9.00
Answer:
-0.2 + 0.5m + 9
Step-by-step explanation: simplify
You have found the following ages in years of 4 gorillas at your local zoo. What is the average age of the gorillas at your zoo? What is the variance? 7, 10, 15,21
Answer:
your answer is 7
Step-by-step explanation:
i may be wrong but i think that is the correct answer oh and Have a good thanksgiving everyone
Answer:
13.3 and 28.2 years
Step-by-step explanation:
from Khan academy
Please help me with question number 2
Answer:
this is easy u need just to put values in the formula
Step-by-step explanation:
putting values in the formula
T =
[tex]2\pi \sqrt{l \div g} [/tex]
T =2×3.14√0.65÷9.8
T= 6.28√0.066
T=6.28×0.25
T=1.617s answer
Suppose the amount of a popular sport drink in bottles leaving the filling machine has a normal distribution with mean 101.5 milliliters (mL) and standard deviation 1.6. If 36 bottles are randomly selected, find the probability that the mean content is less than 102.1 mL
Answer:
0.98778
Step-by-step explanation:
When we are given a random number rod samples, we solve using z score formula
z = (x-μ)/σ/√n, where
x is the raw score = 102.1 mL
μ is the population mean = 101.5 milliliters (mL)
σ is the population standard deviation = 1.6.
n = 36
z = 102.1 - 101.5/1.6/√36
z = 2.25
Probability value from Z-Table:
P(x<102.1) = 0.98778
Hence, If 36 bottles are randomly selected, find the probability that the mean content is less than 102.1 mL is 0.98778
Find the measure of ULE in the triangle below.
Answer:
U = 71 L=60
Step-by-step explanation:
You subtract 180 from 109 to get the measure of U and then you add measure U and E to get 120. Then, you subtract 180 from 120 to get measure L.
15 POINTS IF U ANSWER
Answer:
we need explaining of this question
A polling agency is investigating the voter support for a ballot measure in an upcoming city election. The agency will select a random sample of 400 voters from one region, Region A, of the city. Assume that the population proportion of voters who would support the ballot measure in Region A is 0.46.
Required:
What is the probability that the proportion of voters in the sample of Region A who support the ballot measure is greater than 0.50?
Answer:
0.0544
Step-by-step explanation:
From the given information;
The population proportion of the voters that would support the ballot measures in region A = 0.46
The random sample n = 400 voters
The required probability can therefore be computed as follows:
[tex]P[p_1>0.5] = P \bigg [ \dfrac{p_1-P_1}{\sqrt{\dfrac{P_1(1-P_1)}{n_1}}}>\dfrac{0.5-0.46}{\sqrt{\dfrac{0.46(1-0.46)}{400}}} \bigg][/tex]
[tex]P[p_1>0.5] = P \bigg [ Z>\dfrac{0.04}{\sqrt{\dfrac{0.46(0.54)}{400}}} \bigg][/tex]
[tex]P[p_1>0.5] = P \bigg [ Z>\dfrac{0.04}{\sqrt{6.21\times 10^{-4}}} \bigg][/tex]
[tex]P[p_1>0.5] = P \bigg [ Z>1.605 \bigg][/tex]
[tex]P[p_1>0.5] = 1- P [ Z<1.605 ][/tex]
Using the Excel Function =NORMDIST(1.605)
[tex]P[p_1>0.5] = 1- 0.9456[/tex]
[tex]P[p_1>0.5] =0.0544[/tex]
Therefore, the required probability = 0.0544
Expand the following expression
(9h+2k)^2
A package of 6 pairs of insulated gloves cost $45.54. What is the unit price of the pairs of gloves?
ASAP PLEASE
Answer:
7.59 dollars is the unit price
Step-by-step explanation:
what is h(5)=-5²+3×5
Answer:
the answer will be -10.
What were the coordinates of point B after being translated 4 units left
Answer: B' (x-4,y)
Step-by-step explanation: A figure which is moved from one location to antoher, without changing its size, shape or orientation, is a figure that went through translation.
So, when a point is translated, it means it changed its position.
Point B has x- and y-coordinates: B(x,y)
Point B' after being translated 4 units left means:
(x,y) → (x-4,y)
In other words, translated point B has coordinates
B(x-4, y)
Because moving left is saying the point is moving towards the negative "side" of the x-axis.
Answer Choices:
A) (-6, -1)
B) (6, -1)
C) (-6, 1)
The expression 4x − 2(5x − 1) is equivalent to the expression 2 + 6x.
True
False
It is false that the expressions 4x − 2(5x − 1) and 6x + 2 are equivalent expressions
How to determine the true statement?The expression is given as:
4x − 2(5x − 1)
Open the bracket
4x − 2(5x − 1) = 4x − 10x + 2
Evaluate the like terms
4x − 2(5x − 1) = − 6x + 2
− 6x + 2 and 6x + 2 are not equal expressions
Hence, 4x − 2(5x − 1) and 6x + 2 are not equivalent expressions
Read more about equivalent expressions at:
https://brainly.com/question/2972832
#SPJ2
(7w - 6) +5 (-2.4w + 1)
Answer: The answer would be -5w-1
Step-by-step explanation:
Answer:
xcgvb vgjbnnnnnnnnnn vbjn bvh
Step-by-step explanation:
In the expression (44 - 4) ÷ 2 + 10, which operation should we start with?
Answer: the parenthesis: (44-4)
Step-by-step explanation: In order of operations parenthesis are always first. Then exponents, then multiplication and division, and then addition and subtraction. (PEMDAS)
Help me out please I beg you
Answer:
tesrdxtcfygvoubucewh cwcs wuehcbwch w
Step-by-step explanation:
w edch dwjbsxchwej chwxc
Find the slope of the line passing through the points (-4,7) and (2,-8)
Answer:
[tex]m=\frac{-5}{2}[/tex]
General Formulas and Concepts:
Pre-Algebra
Order of Operations: BPEMDASAlgebra I
Slope Formula: [tex]m=\frac{y_2-y_1}{x_2-x_1}[/tex]Step-by-step explanation:
Step 1: Define
Point (-4, 7)
Point (2, -8)
Step 2: Find slope m
Substitute: [tex]m=\frac{-8-7}{2+4}[/tex]Subtract/Add: [tex]m=\frac{-15}{6}[/tex]Simplify: [tex]m=\frac{-5}{2}[/tex]Which of these figures shows perpendicular lines?
Answer: I think a and b
Step-by-step explanation:
On Monday, Erin ran a mile in 7.5 minutes. On Tuesday, she ran a mile in 6.9 minutes. What was the average time for a mile over those two days, expressed as a fraction?
Answer: 14.4/2
Step-by-step explanation: to find the average time, we add both numbers then divide by how many numbers we have, which is two. So 7.5 + 6.9 = 14.4. we then divide by 2, so 14.4/2.
Help, please I need the answer
Answer: -22
Good Luck!
A water tank leaked 14 gallons of water over eight hours at a constant rate what was the change in the amount of water in gallons in a tank each hour
Answer: the answer would be 1.75 gallons/hour
Step-by-step explanation: if you take the 14 gallons divided by the eight hours, you get 1.75
Answer:
7/4 gallons per hour
Step-by-step explanation:
We have to divide the amount of water lost by the lapse of time. So we get
14/8= 7/4
In a survey of 2,100 people owned a certain type of car, 1365 said they would by that type of car again. What percent of the people surveyed were satisfied with the car?
Answer:
65%
Step-by-step explanation:
Percentage = 1365/2100 *100
= 65%
What is the x-intercept when y = 3x - 6 is graphed?
Answer:
(2,0)
Step-by-step explanation:
Answer:
x intercept (2,0) y intercept is(0,-6)
Step-by-step explanation:
Btw the biggest garden is the rectangular garden
Solve the following expression: (9 x 10) - (30 + 30). Show all steps taken.
Answer:
First multiply each brackets
90-60
30
Step-by-step explanation:
Answer:
9 x 3= 27 and 30 + 30= 60.. so 60- 27= 33, but if you want to do 27- 30.. it would be -33.
Step-by-step explanation:
Hope that answers your question!
Which of the phrases translated the numerical expression 4 x (9-5)? Need answer to both
Answer:
a
Step-by-step explanation:
y+7=4/3(x+3)
A point on this line that is apparent from the given equation is?
Answer:
(-3, -7)
General Formulas and Concepts:
Algebra I
Point-Slope Form: y - y₁ = m(x - x₁)
x₁ - x coordinate y₁ - y coordinate m - slopeStep-by-step explanation:
Step 1: Define
Point-Slope Form: y + 7 = 4/3(x + 3)
Step 2: Break function
Slope m = 4/3
Point (-3, -7)
At the end of week 3 of my baseball team's season, our rcord is 5 wins and 7 looses. Each week after that, we wim 3 games and lose 1 game. At the end of which week will my team have first won at least twice as many games total this season as it has lost?
Answer:
9 weeks
Step-by-step explanation:
Which angles are alternate interior angles explain
Answer:
The answer is D.
Step-by-step explanation:
hope that helps