Find the necessary sample size.
-Scores on a certain test are normally distributed with a variance of 68. A researcher wishes to estimate the mean score achieved by all adults on the test. Find the sample size needed to assure With 95 percent confidence that the sample mean will not differ from the population mean by more Than 4 units.
A)1111
B)8
C)66
D)17

Question

Find the necessary sample size.
-Scores on a certain test are normally distributed with a variance of 68. A researcher wishes to estimate the mean score achieved by all adults on the test. Find the sample size needed to assure With 95 percent confidence that the sample mean will not differ from the population mean by more Than 4 units. 
A)1111
B)8
C)66
D)17

Quizplus · Accepted Answer

To find the sample size, use the formula for the sample size of a mean: n = (Z*σ/E)^2. Here, Z is the Z-score for 95% confidence (1.96), σ is the standard deviation (√68), and E is the margin of error (4). Calculating gives n ≈ 17.

Find the Necessary Sample Size