An energy study in Gainesville, Florida, found that in March 2006, household use of electricity had a mean of 673 and a standard deviation of 556 kilowatt-hours.
a. Suppose the distribution of energy use was normal. Using a table, calculator, or software that can give normal probabilities, find the proportion of households with electricity use greater than 1000 kilowatt-hours.
b. Based on the mean and standard deviation given, do you think that the distribution of energy use actually is normal? Why or why not?