Preliminary road tests conducted by My Best Tire's quality control division suggest that lifetimes of its new, inexpensive radial are normally distributed with the mean lifetime of 30,000 miles and standard deviation of 5,000 miles. Your store has just received the shipment of 1,000 such tires.
a. Determine the probability that a randomly selected tire lasts longer than 38,100 miles?
b. How many tires in your shipment do you expect to last between 27,500 and 33,800 miles?
c. Find out the 94th percentile of this distribution