Suppose the life of a particular brand of calculator battery is approximately normally distributed with a mean of 75 hours and a standard deviation of 9 hours. Complete parts a through c. a. What is the probability that a single battery randomly selected from the population will have a life between 65 and 85 hours? P(65 s i s 85) = D (Round to four decimal places as needed.) b. What is the probability that 4 randomly sampled batteries from the population will have a sample mean life of between 65 and 85 hours? P(65 S x S 85) = D (Round to four decimal places as needed.) 0. If the manufacturer of the battery is able to reduce the standard deviation of battery life from 9 to 7 hours, what would be the probability that 4 batteries randomly sampled from the population will have a sample mean life of between 65 and 85 hours? P(65 5 x S 85) = D (Round to four decimal places as needed.)