In order to estimate the average electric usage per month, a sample of 196 houses was selected, and the electric usage determined.
a. Assume a population standard deviation of 350 kilowatt hours. Determine the standard error of the mean.
b. With a 0.95 probability, determine the margin of error or standard error.
c. If the sample mean is 2,000 KWH, what is the 95% confidence interval estimate of the population mean?