Sammy starts her hike at 230 feet below sea level. When she reaches the end of the hike, she is still below sea level at −138 feet. What was the change in elevation from the beginning of Sammy's hike to the end of the hike?

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?