X = a ^ 2 + 2 + 1/(a ^ 2)

y = a ^ 2 - x + 1/(a ^ 2)

xy=?

Monthly water bills for a city have a mean of $108.43 and a standard deviation of $32.09. find the probability that a randomly selected bill will have an amount greater than $155, which the city believes might indicate that someone is wasting water. would a bill that size be considered unusual?