A study indicates that 18- to 24- year olds spend a mean of
115 minutes watching video on their smartphones per month. Assume
that the amount of time watching video on a smartphone per month is
normally distributed and that the standard deviation is 15 minutes.
Complete parts (a) through (d) below.
a. What is the probability that an 18- to 24-year-old spends
less than
95 minutes watching video on his or her smartphone per
month?
(Round to four decimal places as needed.)
b. What is the probability that an 18- to 24-year-old spends
between
95 and 135 minutes watching video on his or her smartphone
per month?
(Round to four decimal places as needed.)
c. What is the probability that an 18- to 24-year-old spends
more than
135 minutes watching video on his or her smartphone per
month?
(Round to four decimal places as needed.)
d. Five percent of all 18- to 24-year-olds will spend less
than how many minutes watching video on his or her smartphone per
month?