A study indicates that​ 18- to​ 24- year olds spend a meanof

140140

minutes watching video on their smartphones per month. Assumethat the amount of time watching video on a smartphone per month isnormally distributed and that the standard deviation is

1515

minutes. Complete parts​ (a) through​ (d) below.

a.

What is the probability that an​ 18- to​ 24-year-old spends lessthan

120120

minutes watching video on his or her smartphone per​ month?Theprobability that an​ 18- to​ 24-year-old spends less than

120120

minutes watching video on his or her smartphone per month is

nothing.

​(Round to four decimal places as​ needed.)

b.

What is the probability that an​ 18- to​ 24-year-old spendsbetween

120120

and

170170

minutes watching video on his or her smartphone per​ month?Theprobability that an​ 18- to​ 24-year-old spends between

120120

and

170170

minutes watching video on his or her smartphone per month is

nothing.

​(Round to four decimal places as​ needed.)

c.

What is the probability that an​ 18- to​ 24-year-old spends morethan

170170

minutes watching video on his or her smartphone per​ month?Theprobability that an​ 18- to​ 24-year-old spends more than

170170

minutes watching video on his or her smartphone per month is

nothing.

​(Round to four decimal places as​ needed.)

d.

OneOne

percent of all​ 18- to​ 24-year-olds will spend less than howmany minutes watching video on his or her smartphone per​month?

OneOne

percent of all​ 18- to​ 24-year-olds will spend less than

nothing

minutes watching video on his or her smartphone per month.

​(Round to two decimal places as​ needed.)