What is the slant height of the cone

What number produces an irrational number when multiplied by -1.25

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?

The answer is 7.2 how would you put this as money