Electricity bills: According to a government energy agency, the mean monthly household electricity bill in the United States in 2011 was $108.87. Assume the amounts are normally distributed with standard deviation 3 18.00. Use the TI84 Plus calculator to answer the following. (a) What proportion of bills are greater than $134? (b) What proportion of bills are between $83 and $145? (:1 What is the probability that a randomly selected household had a monthly bill less than $118? Round the answers to at least four decimal places