I need help with this question i have for my statistics class

Which is a graph of a proportional relationship?

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?

In which direction does the left side of the graph of this function point? a(x) = 3x - x2 + 4x - 2