An elevator is supported by a wire cable that can withstand a mean stress of 27,500 lb/in2 with a standard deviation of 700 lb/in2 . The load on the elevator is a random variable that causes a stress with a mean value of 24,000 lb/in2 and a standard deviation of 2,250 lb/in2 . If the load on the elevator and the strength of the cable are normally distributed, find the probability of failure of the cable.