The file Energy contains the average residential price for electricity in cents per kilowatt hour in each of the 50 states and the District of Columbia during a recent year.

a. Compute the mean, variance, and standard deviation for the population.

b. What proportion of these states has an average residential price for electricity within ±1 standard deviation of the mean, within ±2 standard deviations of the mean, and within ±3 standard deviations of the mean?

c. Compare your findings with what would be expected based on the empirical rule. Are you surprised at the results in (b)?