The time that a butterfly lives after emerging from its chrysalis can be modelled by a random variable T, the model here taking the probability that a butterfly survives for more than t days as:

P(T>t) = 36/ (6+t)^2, t>=0

a. What is the probability that a butterfly will die within 5 days of emerging?
b. Calculate the mean lifetime of a butterfly after emerging from its chrysalis.