Thicknesses of shims are normally distributed with mean 1.5 mm and standard deviation 0.2 mm. Three shims are stacked, one atop another. a) Find the probability that the stack is more than 5mmthick....

Thicknesses of shims are normally distributed with mean 1.5 mm and standard deviation 0.2 mm. Three shims are stacked, one atop another. a) Find the probability that the stack is more than 5mmthick. b) Find the 80th percentile of the stack thickness. c) What is the minimum number of shims to be stacked so that the probability that the stack is more than 5 mm thick is at least 0.99?