Question 464991
The mean of the exponential function is {{{10 = 1/alpha}}}.  ==> {{{alpha = 1/10}}}.
==> Cdf is {{{F(x) = 1 - 1/e^(alpha*x) = 1 - 1/e^(x/10)}}}
==> {{{F(12) = 1 - 1/e^(12/10) = 1 - 1/e^(6/5) = 0.6988}}}

==> {{{F(6) = 1 - 1/e^(6/10) = 1 - 1/e^(3/5) = 0.4512}}}

==> {{{1 - F(30) = 1 - ( 1 - 1/e^(30/10)) = 1/e^3 = 0.0498}}}