Question

You are trying to estimate the average amount a family spends on food during a year. In the past the standard deviation of the amount a family has spent on food during a year has been approximately $900. If you want to be 99% sure that you have estimated average family food expenditures within $50, how many families do you need to survey? Round your answer up to the nearest whole number, if necessary.

Answer 1

the number of families needed for the survey is 2,157

Explanation:

The computation of the number of families needed for the survey is shown below:

Given that

The Standard deviation is $900

Service level = 99%

z value at 99% = 2.58

Expenditures = $50

Based on the above information

The number of families needed for the survey is

`n = ((zs)/(E))^2\\\\= ((2.58* 900)/(50))^2`

= 2,157

Hence, the number of families needed for the survey is 2,157