(i)[2]
Find the probability that, in one $8$-day holiday period, exactly $2$ of the days are ones on which Martin is playing computer games when his friend phones.
(ii)[1]
Another holiday period lasts $12$ days. State, with a reason, whether it is appropriate to use a normal approximation to find the probability that Martin is playing computer games when his friend phones on fewer than $7$ days.
(iii)[5]
Find the probability that, in a $40$-day holiday period, there are at least $13$ days on which Martin is playing computer games when his friend phones.