Question 331510
if x is exponentially distributed then 

{{{fx = (1/mu) *e^(-x/mu)}}}

{{{ P)x>a) = e^(-a/mu)}}}

in part 1, mu=3.6 and a=9  

so {{{P(x>9) = e^(-9/3.6) =0.082}}} or 8.25%

in part 2, mu=2.5 and a =9

so {{{P(x>9) =e^(-9/2.5) =0.0273}}} or 2.7%