The level curves of the surface z = x^2 + y^2 are circles in the xy-plane centered at the origin. without computing the gradient, what is the direction of the gradient at (- 3,- 5) and (5,2) (determined up to a scalar multiple)?

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?