PLEASE HELP! Find the missing part.

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?

Can someone check if i did this correct. it’s number 4 if you’re wondering.

Which letters from the table represent like terms? a and b b and c a and d b and d