Find the necessary sample size.
-The monthly earnings of a group of business students are are normally distributed with a standard deviation of 545 dollars. A researcher wants to estimate the mean monthly earnings of all business
Students. Find the sample size needed to have a confidence level of 95% and a margin of error of
128 dollars.
A)2
B)5
C)61
D)70

Question

Find the necessary sample size.
-The monthly earnings of a group of business students are are normally distributed with a standard deviation of 545 dollars. A researcher wants to estimate the mean monthly earnings of all business
Students. Find the sample size needed to have a confidence level of 95% and a margin of error of
128 dollars. 
A)2
B)5
C)61
D)70

Quizplus · Accepted Answer

To find the sample size, use the formula for the sample size of a mean: n = (Z*σ/E)^2. For a 95% confidence level, Z is approximately 1.96. Plugging in the values: n = (1.96*545/128)^2 ≈ 70.

Find the Necessary Sample Size