Question

Many people consider their smartphone to be essential! Communication, news, maps, 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 13.75 hours with a standard deviation of 2.2 hours. Then the battery needs to be recharged. Assume the battery life between charges is normally distributed. (a) Find the probability that with heavy use, the battery life exceeds 14 hours. (b) Inverse Normal Distribution 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?

          Many people consider their smartphone to be essential!
Communication, news, maps, 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 13.75 hours with a standard deviation
of 2.2 hours. Then the battery needs to be recharged.
Assume the battery life between charges is normally
distributed.
(a)
Find the probability that with heavy use, the battery life
exceeds 14 hours.
(b)
Inverse Normal Distribution 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?

Added by Antonia H.

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