For the past 65 years, the mean high temperature in Sacramento on

May 15th was 78.4 ºF with a standard deviation of s = 8.1 ºF. Compute the interval that is within one standard deviation of the sample mean. Give the the lower endpoint of your interval as your answer.
A company manufactures tennis balls. A sample of 25 balls are dropped onto a concrete surface from a height of 100 inches. The mean bounce height is 55.1 inches with a standard deviation of 4.3 inches. Compute the interval that is within two standard deviations of the sample mean. Give the the lower endpoint of your interval as your answer.