We wish to estimate the population mean of a variable that has standard deviation 70.5. We want to estimate it with an error no greater than 5 units with probability 0.99. How big a sample should we take from the population? What happens if the standard deviation and the margin of error are both doubled?

a) The large sample size 'n' = 1320.59

b) If the standard deviation and the margin of error are both doubled also the sample size is not changed.

Step-by-step explanation:

Explanation:-

a)

Given data the standard deviation of the population

σ = 70.5

Given the margin error = 5 units

We know that the estimate of the population mean is defined by

that is margin error =

cross multiplication , we get

√n = 36.34

squaring on both sides , we get

n = 1320.59

b) The margin error of the mean

the standard deviation and the margin of error are both doubled

  √n = zₓ2σ/2M.E

  √n = 36.34

squaring on both sides , we get

     n = 1320.59

If the standard deviation and the margin of error are both doubled also the sample size is not changed.

maximum area = xy = (16)(32) = 512 ft2

to maximize the area of the garden, the side of the fence parallel to the side of the house should be 32 ft long, and the other two sides should both have length 16 ft.'

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