2. a laptop company claims up to 9.1 hours of wireless web usage for its newest laptop battery life. however, reviews on this laptop shows many complaints about low battery life. a survey on battery life reported by customers shows that it follows a normal distribution with mean 8.5 hours and standard deviation 39 minutes. (a) what is the probability that the battery life is at least 9.1 hours? 0.178 (b) what is the probability that the battery life is less than 7.9 hours? 0.178 (c) what is the time of use that is exceeded with probability 0.9? 7.67 hours