A Cepheid variable star is a star whose brightness alternately increases and decreases. For a certain star, the interval between times of maximum brightness is 4.2 days. The average brightness of this star is 3.0 and its brightness changes by ±0.25. In view of these data, the brightness of the star at time t, where t is measured in days, has been modeled by the function B(t) = 3.0 + 0.25 sin 2πt 4.2 . (a) Find the rate of change of the brightness after t days. dB dt =

Answers

Answer 1

Answer:

a) [tex]\frac{dB}{dt} = \frac{5\pi}{4.2} \cdot \cos \left(2\pi\cdot \frac{t}{4.2} \right)[/tex], b) [tex]\frac{dB}{dt}\approx 5.595[/tex]

Step-by-step explanation:

a) The rate of change of the brightness of the Cepheid can be determined by deriving the function in time:

[tex]\frac{dB}{dt} = \left(\frac{2\pi}{4.2} \right)\cdot 0.25\cdot \cos (2\pi\cdot \frac{t}{4.2})[/tex]

[tex]\frac{dB}{dt} = \frac{5\pi}{4.2} \cdot \cos \left(2\pi\cdot \frac{t}{4.2} \right)[/tex]

b) The rate of increase after one day is:

[tex]\frac{dB}{dt} = \frac{5\pi}{4.2} \cdot \left(2\pi \cdot \frac{1}{4.2} \right)[/tex]

[tex]\frac{dB}{dt}\approx 5.595[/tex]


Related Questions

express 0.8342 as a fraction A: 8342/10 B: 8342/1000 C: 8342/10000

Answers

Answer:

[tex]\frac{8342}{10000} \\ [/tex]

Answer C is correct

Step-by-step explanation:

[tex]0.8342 = \frac{8342}{10000} [/tex]

To check whether this correct or wrong.

[tex]0.8342 \times 10000 = 8342[/tex]

hope this helps

brainliest appreciated

good luck! have a nice day!

The decimal 0.8342 expressed as a fraction is (c) 8342/10000

How to express the decimal 0.8342 as a fraction.

From the question, we have the following parameters that can be used in our computation

The decimal 0.8342

Express the decimal 0.8342 as a fraction

So, we have the following representation

Fraction = 8342/10000

When the fraction is simplified, we have

Fraction = 8342/10000

Hence, the decimal 0.8342 as a fraction is (c) 8342/10000

Read more about fraction at

brainly.com/question/78672

#SPJ6

Find the area of the circles. Use 3.14 for . (Show work for full credit)

Answers

Answer:

Figure 1

The area of circle is 452.16 inches ².

Figure 2

The area of circle is 615.44km².

Figure 3

The area of circle is 132.665 km².

4) The radius of circle is 9 cm and diameter is 18cm.

When Ravi brought 3 friends to his house after school, his mother gave them a box of pretzels and a box of crackers. She told them to share the snacks equally among themselves and to give her any that were leftover.
The boys opened the boxes and found a total of 26 pretzels and 35 crackers.
How many pretzels and crackers did the boys give to Ravi's

Answers

Answer:

6 pretzels and 8 crackers

Step-by-step explanation:

Since his mom told him to give her the remaining, 6*4= 24 giving to his mom 2 pretzels and 8*4=32 so he has to give his mom 3 crackers. This way him and his friends have the same amount of snacks.

Hope you find it useful.  Good night

First of all, we need to determine how many people are sharing the snacks. Ravi and his 3 friends would be four people.

Important:
4 friends

Next, we have to share the snacks equally, that means that each person gets the same exact amount of snacks.

Important:
4 friends
same exact amount if snacks for each person

Now, since you are seperating them equally amongst the four friends, we have to divide but you cannot go above the number 26, or 35.

4x7 gives you 28, although 26 is not divisble by 26, its ok to have extra so each child will have 4x6 (24) 6 crackers.

4x8 gives you 32 and you wouldn"t choose 4x6, or 7 because you will either have too many or too little.

So, each child will get 6 pretzels and 8 crackers. It is okay if there are extra snacks.

A store has 80 modems in its inventory, 30 coming from Source A and the remainder from Source B. Of the modems from Source A, 20% are defective. Of the modems from Source B, 8% are defective. Calculate the probability that exactly two out of a sample of five modems selected without replacement from the store’s inventory are defective.

Answers

Answer:

0.102

Step-by-step explanation:

The number of defective modems in the inventory is 20% * 30 + 8% * 0.50 =10 (out of 80)

Note that the number of defectives in the inventory is fixed i.e. we are told that there is 1/8 probability that a modem in the inventory is defective, but rather that exactly 1/8 of all modems are defective.

The probability that exactly two modems in a random sample of five are defective is :

(10↓2)(70↓3) / (80↓5) = 0.102

Solve x for the diagram below.

Answers

Answer:

20°

Step-by-step explanation:

These angles add up to 90° so we have:

x + 2x + x + 10 = 90

4x + 10 = 90

4x = 80

x = 20°

The square shown at the bottom left corner indicates that it is 90 degrees.

To find the value of x you must set the equation up to equal 90 degrees.

x + 2x + (x + 10) = 90
3x + x + 10 = 90
4x + 10 = 90
Subtract 10 from both sides.
4x = 80
Divide both sides by 4.
x = 20

Answer: x = 20

Please give answer with explanation of formula. Please reply fast I have exam.

Answers

Answer:

D

Step-by-step explanation:

3/40 * 2.5/2.5 = 7.5/100 = 0.075

A circular plate has circumference of 37.7cm. Calculate the diameter of the plate

Anyone that answers I will mark as brilliant

Answers

Answer:

12.0

Step-by-step explanation:

d(pi)=37.7

d=12.0

What is X:Compute
|x|=−4

Answers

Answer:

The answer is No Solution

Answer:

No solution

Step-by-step explanation:

There is no solution to this question.

Since the x is an absolute number, the answer cannot be -4. It would have to equal 4

So if that x was a -4 it would equal 4 since it is in absolute value brackets

Maddie is packing moving boxes. She has one 3 cubic-foot box and one 6 cubic-foot box. How many cubic feet of clothing can she fit in the two boxes?

8 9 10 12

Answers

Answer:

She can fit 9 cubic feet of clothing in the two boxes.

Step-by-step explanation:

She can fit a total of 3 cubic feet of clothing in one box, and the other she can fit a total 6 cubic feet.

3 + 6 = 9

Answer:

9 cu ft.

Step-by-step explanation:

That is the sum of the capacities of the 2 boxes

=  3 + 6

= 9 cu ft.

Bob has 54 more five-dollar bills than ten-dollar bills. The number of five-dollar bills he has
is 7 times that of ten-dollar bills. How many dollars does Bob have in all?

Answers

Answer:5000 sum

Step-by-step explanation:

A textile manufacturer has historically found an average of 0.1 flaws per square meter of cloth. Let X be the number of flaws in a bolt of 2000 square meters of cloth. How is X distributed

Answers

Answer:

Poisson distribution

Step-by-step explanation:

Given that :

There is an average of 0.1 flaws per square meter of cloth

So X = the number of flaws in a bolt of 2000 square meters of cloth.

The objective is to deduce how is X distributed.

Well, we can say X undergoes Poisson distribution.

Because, the flaw can be randomly positioned on the cloth and also dictate  how many times the event is likely to occur within a specified period of time.

Most time Poisson distribution is majorly used for independent events.

An independent is an event which contains two types of events occuring at a time say event [tex]E_1[/tex] and event [tex]E_2[/tex] and the event [tex]E_1[/tex] does not in any way affects the occurrence of the event [tex]E_2[/tex] .

The table represents an exponential function. A 2-column table has 4 rows. The first column is labeled x with entries 1, 2, 3, 4. The second column is labeled y with entries 0.25, 0.125, 0.0625, 0.03125. What is the multiplicative rate of change of the function? 0.2 0.25 0.5 0.75

Answers

Answer:

0.5 or C on edge2021

Step-by-step explanation:

The multiplicative rate of change of the function will be:

0.5

What is a Multiplicative rate of change?

The multiplicative rate of change is the common factor that the numbers can be multiplied with to get the succeeding figures.

For instance, if 0.25 is multiplied by 0.5, the result will be 0.125. Also, if 0.125 is multiplied by 0.5, the result will be 0.0625.

Learn more about the multiplicative rate of change here:

https://brainly.com/question/4319809

#SPJ9

According to the U.S. Census Bureau, the mean of the commute time to work for a resident of Boston, Massachusetts, is 27.3 minutes with a standard deviation of 8.1 minutes. What minimum percentage of commuters in Boston has a commute time within 2 standard deviations of the mean

Answers

Answer:

By the Chebyshev Theorem, at least 75% of commuters in Boston has a commute time within 2 standard deviations of the mean

Step-by-step explanation:

Chebyshev Theorem

The Chebyshev Theorem can also be applied to non-normal distribution. It states that:

At least 75% of the measures are within 2 standard deviations of the mean.

At least 89% of the measures are within 3 standard deviations of the mean.

An in general terms, the percentage of measures within k standard deviations of the mean is given by [tex]100(1 - \frac{1}{k^{2}})[/tex].

What minimum percentage of commuters in Boston has a commute time within 2 standard deviations of the mean

By the Chebyshev Theorem, at least 75% of commuters in Boston has a commute time within 2 standard deviations of the mean

95% of commuters in Boston has a commute time within 2 standard deviations of the mean

Empirical rule

Empirical rule states that for a normal distribution, 68% of the values are within one standard deviation from the mean, 95% of the values are within two standard deviation from the mean and 99.7% of the values are within three standard deviation from the mean.

Hence, 95% of commuters in Boston has a commute time within 2 standard deviations of the mean

Find out more on Empirical rule at: https://brainly.com/question/10093236

An appliance repairman charges $25 plus $40 per hour for house calls. Write the rule as an equation that relates hours worked x and his fee y.

Answers

To get the total fee, you need to multiply the hourly rate by number of hours worked and add that to the flat fee of $25.

The equation would be y = 40x + 25

An amount was invested at r% per quarter. What value of r will ensure that accumulated amount at the end of one year is 1.5 times more than amount invested? Correct to 2 decimal places

Answers

Answer:

25.75 %  interest rate

Step-by-step explanation:

Given:

Amount was invested = r% per quarter  

Amount invested = P

Rate of interest = r %  per quarter

Time (n) = 4  Quarters

Computation:

A = P(1 + r/100)ⁿ

According to question.

⇒ A = P + 1.5P  = 2.5P

⇒ 2.5P = P(1 + r/100)⁴

⇒ 2.5  = (1  + r/100)⁴

⇒ 1 + r/100  =  1.2575

⇒ r/100 = 0.2575

⇒ r = 25.75

25.75 %  interest rate

3. (03.06)
Choose the point-slope form of the equation below that represents the line that passes through the points (-6, 4) and (2,0). (2 points)

Answers

Answer:

work is shown and pictured

How can you use mathematics to help scientists explore Martian Craters ? 

Answers

Answer:

Mathematics could make scientists to have a preliminary understanding of the dimensions, perimeters, areas and volumes of different craters on Mars.

Step-by-step explanation:

Martian Craters are series of craters formed on the surface of Mars. The study of a planets crater gives an understanding of the properties of matter that lies under the crater.

Mathematics can be applied to determine the dimensions, perimeter, area and volume of the features of a crater using appropriate conversions and theorems.

The Pi in the sky theorem can be applied to determine the area and perimeter, even volume of different craters on the Mars surface. Also, eingenfunction expansion theorem gives a preliminary knowledge of the craters.

By measurements and conversions processes, the features of Martian crater could be studied from images.

Please help meee

Which number line model represents the expression -2/5 + 4/5:

Answers

The number line model that represents the expression -2/5 + 4/5 is: Option B

How to solve Inequality on number line?

To plot an inequality, such as x > 2, on a number line, first draw a circle over the number (e.g., 2). Then if the sign includes equal to (≥ or ≤), fill in the circle. If the sign does not include equal to (> or <), leave the circle unfilled in.

Now, in this case, the operation to solve is:

-2/5 + 4/5

Solving this gives 2/5

Now, since the operation shows a negative and positive fraction with the solution being positive, then we can easily say that Option B is the correct answer to the problem

Read more about Inequality on number line at: https://brainly.com/question/24372553

#SPJ1

Which of the following are solutions to the quadratic equation? Check all that apply x^2 + 12x + 36 = 7

Answers

Answer:

x = -6 + [tex]\sqrt{7}[/tex], x = -6 - [tex]\sqrt{7}[/tex]

Step-by-step explanation:

(x + 6)² = 7

x + 6 = + or - [tex]\sqrt{7}[/tex]

x = -6 + [tex]\sqrt{7}[/tex], x = -6 - [tex]\sqrt{7}[/tex]

The solution of the quadratic equation is x = -6 +√7, x = -6 - √7.

What is a quadratic equation?

A quadratic equation is a polynomial with a degree of 2 or the maximum power of the variable is 2 in quadratic equations. It has two solutions as its maximum power is 2.

Completing the square entails writing a quadratic in the form of a squared bracket and, if necessary, adding a constant. Finding the maximum or minimum value of the function and when it occurs is one application of completing the square.

Given that the quadratic equation is x² + 12x + 36 = 7.

(x + 6)² = 7

x + 6 = ±√7

x = -6 + √7 , x = -6 - √7

To know more about quadratic equations follow

https://brainly.com/question/25841119

#SPJ2

7. How much alcohol must be added to 480 grams of hand sanitizer that is 24% alcohol to
make it a hand sanitizer that is 40% alcohol? Correct your answer to the nearest whole
number

Answers

Answer:

the amount of alcohol to be added is 128 grams

Step-by-step explanation:

Given that:

The initial mass of the hand sanitizer = 480 grams

The initial strength of the hand sanitizer = 24 %

The new strength of the hand sanitizer = 40%

The objective here is to determine the final amount of alcohol that is to be added to get the new strength of the alcohol

First; let's find the mass of alcohol in the initial hand sanitizer;

SO;

= 24  % of 480

[tex]=\dfrac{24}{100}*480[/tex]

= 115.2 grams

If y should represent the mass of the alcohol added to have 40%; we have

The new amount of the alcohol to be[tex](115.2 + y) \ grams[/tex]

The new amount of the hand sanitizer will be[tex](480 + y) grams[/tex]

For the new strength of sanitizer:

40 % of (480 + y) = (115.2 + y)

[tex]0.4 *(480 + y) = (115.2 + y) \\ \\ 192 + 0.4 y = 115.2 + y \\ \\ y (1 - 0.4) = 192 - 115.2 \\ \\ y= \dfrac{76.8}{0.6} \\ \\ y = 128 \ grams[/tex]

Thus ; we can conclude that the amount of alcohol to be added is 128 grams

You play a game that requires rolling a six sided die then randomly choosing a card from a deck containg 8 red cards ,6 blue cards and 8 yellow cards whats the probability that younroll a 3 on the due and choose a red card

Answers

Answer:

2/33

Step-by-step explanation:

Probability that a 3 is rolled on the die = 1/6 (equal chance of rolling any number)

Probability of choosing a red card = 8/22 (8 red cards, 22 cards in total)

8/22 = 4/11

Probability of rolling a 3 AND choosing a red card = 1/6 x 4/11

= 4/66

= 2/33

6500 rounded to the nearest thousand is __. Enter your answer without commas

Answers

Answer:

7000

Step-by-step explanation:

If the hundreds place is higher than 5, then add 1 to the thousands place.

Which expression best represents the situation?
Select the expression that best matches the scenario.
O4 + x + 3
4(x + 3)
4.3
4x + 3
Tyson bought a burger for himself and
each of his 3 friends. He left a tip of $3.
Which expression could represent
the amount of money Tyson spent?
Explain your thinking.
Help plz

Answers

Answer:509

Step-by-step explanation:600

Evaluate: 5-^2 =
pls help

Answers

Answer:

1/25

Step-by-step explanation:

5^-2

We know that a^ -b = 1/ a^b

5^-2 = 1/ 5^2

       = 1/25

SOMEONE PLEASE HELP ME ASAP PLEASE!!!​

Answers

Answer:

7.1

Step-by-step explanation:

d = sqrt(7^2 + -1^2)= sqrt(50)=7.1

Answer:

by using distance formula

putting values

d=√(-1-6)²+(-4--5)²

d=√(-7)²+(1)²

d=√49+1

d=√50

d=5√2=7.1

Goodlife charges its members $30 per month for a gym membership. They currently have 75 clients.
Research has shown that for every $2 increase in their membership price they will lose 3 clients. If they want to maximize their revenue, how much should Goodlife charge per membership? What will their maximized revenue be?

Answers

They should charge $40 per membership, and they will make a maximum revenue of $2400

if f(x)=ln(sin(2x)), f''(π/4) is equal to​

Answers

Use the chain rule to compute the second derivative:

[tex]f(x)=\ln(\sin(2x))[/tex]

The first derivative is

[tex]f'(x)=(\ln(\sin(2x)))'=\dfrac{(\sin(2x))'}{\sin(2x)}=\dfrac{\cos(2x)(2x)'}{\sin(2x)}=\dfrac{2\cos(2x)}{\sin(2x)}[/tex]

[tex]f'(x)=2\cot(2x)[/tex]

Then the second derivative is

[tex]f''(x)=(2\cot(2x))'=-2\csc^2(2x)(2x)'[/tex]

[tex]f''(x)=-4\csc^2(2x)[/tex]

Then plug in π/4 for x :

[tex]f''\left(\dfrac\pi4\right)=-4\csc^2\left(\dfrac{2\pi}4\right)=-4[/tex]

Rachel owns as twice as many beanie babies as Kaye. Alexia owns 1/3 as many beanie babies as Rachel. If Kaye owns 63 beanie babies,how many does Alexia owns?

Answers

Answer:

42

Step-by-step explanation:

Let the number of beanie babies Kaye has be x

according to question

Rachel owns as twice as many beanie babies as Kaye

number of beanie babies Rachel has : 2*x = 2x

Also,

Alexia owns 1/3 as many beanie babies as Rachel

number of beanie babies Alexia has : 1/3(2x) = 2x/3

It is given that Kayes has 63 beanie babies

thus x = 63

Thus,

Number of beanie babies Alexia has = 2x/3 = 2*63/3 =2*21 = 42

Aurora saved $850. Ahe used 35% of her savings on a new TV. How much did the TV cost?

Answers

Multiply her savings by the percent spent:

850 x 0.35 = 297.50

The tv cost $297.50

Answer:

the price of TV is = 297.5$

Step-by-step explanation:

all money= 850$

purchased money= 35% of all money ==> 850 ( 35%) = 297.5$

A triangular plate with base 3 m and height 5 m is submerged vertically in water so that the tip is even with the surface. Express the hydrostatic force against one side of the plate as an integral and evaluate it. (Round your answer to the nearest whole number. Use 9.8 m/s2 for the acceleration due to gravity. Recall that the weight density of water is 1000 kg/m3.)

Answers

Answer:

The hydro-static force [tex]F=245000N[/tex]

Step-by-step explanation:

given data

base = 3 m

height = 5 m

density of water = 1000 kg/m3

Acceleration due to gravity = 9.8

The area if the strip needs to be calculated using similar triangular formula as well as the hydrostatic force

CHECK THE ATTACHMENT BELOW FOR DETAILED EXPLANATION

Other Questions
is Naci a metal or none metel Looking at the histogram, where would the median fall? #1. True or False: Many immigrants lived in poverty once they arrived in America.#2. Which industries had the greatest impact on westward expansion? Solve -8(x+6)-1=5(x-2) for x What is the main problem with the following critique? Ive never liked horses, so I didnt think your speech was very interesting. Besides, the way your voice sounds has always bugged me.a.It is not objective.b.It is not ethical.c.It is not specific.d.It is not behavior focused. Describe the solutions of the following system in parametric vector form,and provide a geometric comparison with the solution set .x1 + 3x2- 5x3 = 4x1+ 4x2 - 8x3 = 7 -3x1- 7x2 +9x3 =6 Which of the items below are true about acid rain? (6x+11x+9)+(3x-x-8) please help Required informationAn internal control system consists of the policies and procedures managers use to protect assets, ensure reliable accounting, promote efficient operations, and uphold company policies. It can prevent avoidable losses and help managers both plan operations and monitor company and human performance. Principles of good internal control include establishing responsibilities, maintaining adequate records, insuring assets and bonding employees, separating recordkeeping from custody of assets, dividing responsibilities for related transactions, applying technological controls, and performing regular independent reviews. Sarbanes-Oxley Act requires each of the following: A. An effective internal control.B. Light penalties for violators.C. Auditors must evaluate internal controls.D. Auditor's work overseen by Public Accounting Board. Which points are on the graph of f(x)=(1/3)^x?Select each correct answer 1. (-1, -1/3)2. (3, 27)3. (-2, 9)4. (0, 1) function of a mitochondion Suppose you want to invest $10,000. You have two options: Option #1: Invest in municipal bonds with an expected return of 8.00%, or Option #2: Invest in the corporate bonds of Jefferson & Alexander Inc. which are offering an expected return of 10.00% Assume that your decision is based solely on your tax situation. If everything else is the same for both bonds, at what tax rate would you be indifferent between these two bond investments? right auricale is bigger then left aurical, why? I will mark you brainliest! How much money did Nikki orginally invest? 2) An algorithm that takes in as input an array with n rows and m columns has a run time of O(nlgm). The algorithm takes 173 ms to run in an input array with 1000 rows and 512 columns. How long will the algorithm take to run on an input array with 1500 rows and 4096 columns? (Note: For ease of calculation, please use a base of 2 for your logarithm.) The integration of flower farming in Kenya into global economy creates additional pressure for the ecosystem and the environment in Kenya. The major concern is due to the following. A. More pollution in Naivasha lake B. Less water resources for locals C. extensive use to water flowersD. All of these The color is repellent, almost revolting; a smoulderingunclean yellow, strangely faded by the slow turningsunlight. It is dull yet lurid orange in some places, a sicklysulphur tint to others.Which phrase best shows a disgusted tone?A. Repellent, almost revoltingB. Strangely fadedC. In some placesD. Slow-turning sunlight Complete the equation of the line through (6,5) and (-3, -3).Use exact numbers. Change the following sentences into interrogative 1 He was present 2 They know me 3 She drinks coffee daily 4 He can be sleeping 5 He has got a golden ring (a) Find an angle between 0 and 2 that is coterminal with 1910.