Suppose the life of a particular brand of calculator battery is approximately non'nally distributed with a mean of T5 hours and a standard deviation of?) 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 1'0 and 80 hours? PHI] 5 St S 80} = 0.4246 [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 lite of between 70 and Bi] hours? PUD SiSSU) = [Round to four decimal places as needed.)