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.At 95% confidence, the size of the margin of error is
A) 1.96.
B) 50.00.
C) 98.00.
D) 42.00.

Question

Quizplus · Accepted Answer

The margin of error is calculated using the formula: Margin of Error = Z * (σ/√n), where Z is the Z-score for 95% confidence (1.96), σ is the population standard deviation (450), and n is the sample size (81). Calculating this gives 1.96 * (450/√81) = 1.96 * 50 = 98.00.

In Order to Estimate the Average Electric Usage Per Month