Exhibit 8-4 In Order to Estimate the Average Electric Usage Per Month

question 107

Multiple Choice

Exhibit 8-4
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.
-Refer to Exhibit 8-4. If the sample mean is 1,858 KWH, the 95% confidence interval estimate of the population mean is

• A)1,760 to 1,956 KWH
• B)1,858 to 1,956 KWH
• C)1,760 to 1,858 KWH
• D)none of these alternatives is correct