Find the missing side in the triangle ​

How do i do this? i don’t understand

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?

To determine the number of deer in a forest a forest ranger tags 280 and releases them back