In order to estimate the average electric usage per month, a sample of 81 houses was selected and the electric usage was determined.Assume a population standard deviation of 450 kilowatt-hours.The standard error of the mean is
A) 450.
B) 81.
C) 500.
D) 50.

Question

Quizplus · Accepted Answer

The formula for standard error of the mean is:

standard error of the mean = population standard deviation / √(sample size)

Plugging in the given values, we get:

standard error of the mean = 450 / √81 = 450 / 9 = 50

Therefore, the standard error of the mean is 50. Choice D is correct.

In Order to Estimate the Average Electric Usage Per Month