For the past 65 years, the mean high temperature in Sacramento on May 15th was 78

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.