Efficiency experts study the processes used to manufacture items in order to make them as efficient as possible.

Efficiency experts study the processes used to manufacture items in order to make them as efficient as possible. One of the steps used to manufacture a metal clamp involves the drilling of three holes. In a sample of 78 clamps , the mean time was 43.5 seconds. Assume that the population standard deviation is 10 seconds. What is the lower bound of the 98% confidence interval?