I don't actually know what topic this falls under exactly to be honest. The question goes:
In an experiment to study pulses along a nerve fibre, the times between 101 successive pulses were measured. The observations gave a sample mean seconds. Assuming that these data are a random sample from an exponential distribution, calculate
(i) the most likely value for the mean pulse rate per second
(ii) the most likely value for the probability that the time between successive pulses is greater than 20 seconds i.e. .