Question

In order to estimate the average electric usage per month, a sample of 36 houses was selected and the electric usage was determined. Assume a population standard deviation of 330 kilowatt-hours. Find the standard error of the mean.

Answer 1

55

Explanation:

standard error of the mean. is expressed mathematically as;

`SM = (\sigma)/(\sqrt n)`

`\sigma` is the standard deviation

n is the sample size

Given

`\sigma = 330kwh\\n = 36`

Required

Standard error of the mean SM

Substitute the given parameters into the formula shown;

`SM = \frac{330}{\sqrt {36}}\\SM = (330)/(6) \\SM = 55`

Hence the standard error of the mean is 55.