Given two normally distributed populations with equal means and variances of o=100 and o2 = 80, what is the probability that samples of size n = 25 and m = 16 will yield a value of x - x greater than or equal to 8? A certain kind of appliance requires repair on the average once every 2 years. Assuming that the times between repairs are exponentially distributed, what is the probability that such an appliance will work at least 3 years without requiring repairs? The milage (in thousand of miles) that car owners get with a certain kind of radial tire is a random variable having an exponential distribution with 8 = 40. Find the probabilities that one of these tires will last a. at least 20,000 miles; b. at most 30,000 miles.