Maria is making a frame for a rectangular garden. She uses a string to measure the length of the diagonal. Which equation should Maria use to ensure that the frame has 90° angles?

Monthly water bills for a city have a mean of $108.43 and a standard deviation of $36.98. find the probability that a randomly selected bill will have an amount greater than $173, which the city believes might indicate that someone is wasting water. would a bill that size be considered unusual?