An experiment involves randomly selecting a sample of 256 middle managers for study. One item of interest is their mean annual income. The sample mean is computed to be $35,420 and the sample standard deviation is $2,050. What is the standard error of the mean?
A) $5.65
B) $128.13
C) $138.36
D) $2,050
E) $8.01

Question

Quizplus · Accepted Answer

The standard error of the mean is calculated as the sample standard deviation divided by the square root of the sample size:

Standard Error of the Mean = Sample Standard Deviation / sqrt(Sample Size)
Standard Error of the Mean = $2,050 / sqrt(256)
Standard Error of the Mean = $2,050 / 16
Standard Error of the Mean = $128.13

Therefore, the standard error of the mean is $128.13. Option B is the correct answer.

An Experiment Involves Randomly Selecting a Sample of 256 Middle