For one randomly selected person, the day of their next birthday is just as likely to land on any of the 7 days of the week, and this does not depend on any other person’s birthday.
(a)[1]
Determine the probability that, among 10 people chosen at random, none will have their next birthday on Saturday or Sunday.
(b)[3]
Determine the probability that, out of 10 randomly chosen people, fewer than 3 will have their next birthday on a Wednesday.
(c)[5]
Use a suitable approximation to find the probability that, out of 392 randomly chosen people, more than 65 will have their next birthday on a Friday.
Worked solution & mark scheme
This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: “$\frac{9765625}{282475249}=0.0346=\left(\frac57\right)^{10}$” …