Probability maximization.

A postal worker has an operating time T that is exponentially distributed with density:

f(t)=et,........t0

where is an unknown parameter.

a) Given n observations t₁,. . . , t_n, find the probability maximization estimate b for . Find a numeric value for b when we have the following 10 observed operating times:

t_i : 1, 1.4, 2.0, 0.5, 0.7, 2.0, 1.3, 1.1, 1.8, 0.2,

where the unit of time is one minute.

b) Is b an expected estimator for ? Justify the answer

I need help with this, espessially question a). I think i know how to do b) but if you can break them both down it would be helpful