A simple random sample of kitchen toasters is to be taken to determine the mean operational lifetime in hours. Assume that the lifetimes are normally distributed with population standard deviation $\sigma = 28 \text { hours. }$
Find the sample size needed so that a 95 % confidence interval for the mean lifetime will have a margin of error of 4 .
A) 2
B) 385
C) 189
D) 14

Question

A simple random sample of kitchen toasters is to be taken to determine the mean operational lifetime in hours. Assume that the lifetimes are normally distributed with population standard deviation $\sigma = 28 \text { hours. }$
Find the sample size needed so that a  95 %  confidence interval for the mean lifetime will have a margin of error of  4 . 
A) 2
B) 385
C) 189
D) 14

Quizplus · Accepted Answer

The Answer of A simple random sample of kitchen toasters is to be taken to determine the mean operational lifetime in hours. Assume that the lifetimes are normally distributed with population standard deviation $\sigma = 28 \text { hours. }$
Find the sample size needed so that a  95 %  confidence interval for the mean lifetime will have a margin of error of  4 . 
A) 2
B) 385
C) 189
D) 14

A Simple Random Sample of Kitchen Toasters Is to Be σ=28 hours. \sigma = 28 \text { hours. }σ=28 hours.

A Simple Random Sample of Kitchen Toasters Is to Be $\sigma = 28 \text { hours. }$