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snow_tiger [21]
3 years ago
15

A circle has an initial radius of 50 ft when the radius begins decreasing at the rate of 5 5 ​ft/min. What is the rate in the ch

ange of area at the instant that the radius is 26 26 ​ft?
Mathematics
1 answer:
gavmur [86]3 years ago
6 0

Answer:

  -816.8 ft²/min

Step-by-step explanation:

The rate of change of area is the product of the rate of change of radius and the circumference of the circle. At the time of interest, ...

  dA/dt = C·dr/dt = 2πr·dr/dt

  dA/dt = 2π·(26 ft)(-5 ft/min)

  dA/dt = -260π ft²/min ≈ -816.8 ft²/min

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Kamila buys a dress for £30 in a sale. It was advertised "25%off". Kamila says"25% of £30 is £7.50 so i saved £7.50". Explain wh
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Answer:

She was wrong in her analysis because the sales discount of 25% is the discount on the original cost of the dress and not the purchasing cost of the dress as explained below:

Step-by-step explanation:

From the question:

Purchasing cost price of the dress = £30

However, this cost (£30) was after a 25% Sales Discount        

It, therefore, implies that £30 is equal to 75% of the cost price

75% of the original cost price  = £30

100% of the original cost price = (30 x100%)/75%

   Original cost price                 = £40

Therefore the 25% discount / savings on the cost

                                                     = £ (40-30)

                                                      = £10    

She saved £10 by buying the dress at £30 instead of the original cost of £40                                        

                                           

6 0
3 years ago
Sally goes out to lunch and has the option of a soup or a salad and then a turkey, ham, or club sandwich. Which tree diagram cor
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The answer should be B 



3 0
3 years ago
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A random sample of 64 second-graders in a certain school district are given a standardized mathematics skills test. The sample m
svet-max [94.6K]

Answer:

Given : The sample mean score is 51.48 .

            The standard deviation for the population of test scores is 15.

             The nationwide average score on this test is 50.

To Find :  Perform the hypothesis test and compute the P-value?

Solution:

Sample size = n = 64

Since n > 30

So, we will use z test over here

We are supposed to find The school superintendent wants to know whether the second-graders in her school district have greater math skills than the nationwide average.

Hypothesis : H_0:\mu \leq 50\\H_a:\mu>50

Formula of z test : z =\frac{x-\mu}{\frac{\sigma}{\sqrt{n}}}

x = 51.48\\\mu = 50\\\sigma = 15\\ n = 64

Substitute the values

z =\frac{51.48-50}{\frac{15}{\sqrt{64}}}

z =0.789

Find the value of P(z) from z table

p(z)=0.7823

Since we are given that we are supposed to find The school superintendent wants to know whether the second-graders in her school district have greater math skills than the nationwide average.

So, p value = 1-P(z)  = 1-0.7823=0.2177

In general , Level of significance is 0.05

So, p value is greater than alpha.

So, we accept the null hypothesis.

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3 years ago
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What is the slope of the equation Y=5/4x-7/4?
maksim [4K]

Answer:

Step-by-step explanation:

Compare the equation with y = mx + b where m is slope and b is y intercept

y = (5/4)x - (7/4)

Slope = m = 5/4

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2 years ago
PLZ HELP ME IF YOU ARE A MR.BEAST FAN. The sum of 7 and 5 times a number is 48. What are the two numbers? What is the equation a
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Answer:

I´m not a Mr. Beast fan but the answer is 4. 4*12 (which is the sum of 7 and 5) = 48

The equation is (7+5)x=48

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