Suppose the download time of a smart phone app is uniformly

Suppose the download time of a smart phone app is uniformly distributed between 31 and 81 seconds.

Probability download is less than 36 seconds is 0.1

Probability download is less than 43 seconds is .24

Probability download is between 43 and 53 seconds is 0.2

The mean of the given uniform distribution is 56

What is the standard deviation of the given uniform distribution?

Solution

The download time is uniformly distributed between 31 and 81 seconds.

Thus,

f(x)=1/(b-a) for a<x<b

=0 ow

The standard deviation is:

(b-a)/sqrt12

=(81-31)/sqrt12

=50/3.46

=14.45