An environmental scientist is conducting research on a particular type of air pollution. She collects air samples over time and determines the average number of micrograms of the pollution in a cubic meter. Her data are shown in the table below.

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?