At a farm the ratio of cows to horses was 9 to 2 if there were 72 cows at the farm how many horses were there?

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?