If 90% of a certain high performance radial tires last at le…
If 90% of a certain high performance radial tires last at least 30,000 miles, among 20 selected tires at random (a) what is the probability of more than 12 tires will last at least 30,000 miles ? (b) what is the probability of between 8 and 15, exclusive, tires will last at least 30,000 miles ?