(a)[3]
Determine the probability that, in a random selection of $12$ days, Moena sends Pasha a message on at most $9$ of them.
(b)[1]
Moena messages Pasha on $1$ January. Determine the probability that the next day on which she messages Pasha is $5$ January.
(c)[5]
Use an approximation to determine the probability that, over any run of $100$ days, Moena messages Pasha on fewer than $64$ days.