The time between failures for an electrical appliance is exponentially distributed with a mean of 60 months. What is the probability that the next failure will not occur before 150 months have elapsed? A. not in excess of .05 B. in excess of .05 but not in excess of 1 C. in excess of .1 but not in excess of .15 D. in excess of 15 but not in excess of 2 E. in excess of 2