"Talk Time on a Cell Phone Suppose the "talk time" in digital mode on a Motorola Timeport P8160 is normally distributed with mean 324 minutes and standard deviation 24 minutes.
a) What percent of the time will a fully charged battery last at least 330 minutes?
b) What is the probability that a random sample of n = 15 batteries results in a mean talk time of at least 330 minutes?
(c) What is the probability that a random sample of n = 30 batteries results in a mean talk time of at least 330 minutes?