Many people consider their smart phone to be essentiall Communication news Internet entertainment photos and just keeping current are all conveniently possible with a smart phone However the battery better be charged or the phone is useless Battery life of course depends on the frequency duration and type of use One study involving heavy use of the phones showed the mean of the battery life to be 12 75 hours with a standard deviation of 2 3 hours Then the battery needs to be recharged Assume the battery life between charges is normally distributed AUSE SALT a Find the probability that with heavy use the battery life exceeds 13 hours Round your answer to four decimal places b You are planning your recharging schedule so that the probability your phone will die is no more than 5 After how many hours should you plan to recharge your phone Round your answer to the nearest tenth of an hour hours