Suppose that, after measuring the duration of many telephone calls,
a telephone company found their data was well-approximated by the
density function
p(x) = 0.2 e^{-0.2 x} , where x is the duration of a call,
in minutes.

**(a)**
What percentage of calls last between 2 and 3 minutes?

Percent =

**(b)**
What percentage of calls last 2 minutes or less?

Percent =

**(c)**
What percentage of calls last 4 minutes or more?

Percent =

**(d)**
What is the cumulative distribution function,

You can earn partial credit on this problem.