A random sample of 41 glass sheets is obtained and their thi

A random sample of 41 glass sheets is obtained and their thicknesses are measured. The sample mean is

x = 3.040 mm, and the sample standard deviation is s = 0.124 mm.

Assuming that the standard deviation of thickness is 0.124 mm, how many glass sheets must be sampled to construct a 99% confidence interval for the mean glass thickness with a width no larger than 0.05 mm?