a) = Let X = “number of passengers who do not show up” then X ~ Bin(200, 0.03)An airline knows that overall 3% of passengers do not turn up for flights. The

airline decides to adopt a policy of selling more tickets than there are seats on a

flight. For an aircraft with 196 seats, the airline sold 200 tickets for a particular

flight.

(a) Write down a suitable model for the number of passengers who do not turn up

for this flight after buying a ticket.

By using a suitable approximation, find the probability that

(b) more than 196 passengers turn up for this flight,

(c) there is at least one empty seat on this flight.

As p is very small, the Poisson approximation may be used. X ~ Po(6)

b) = P(X < 4 ) = 0.1512 (from Cumulative binomial Tables)

c) I stuck on part 'c', because the correct answer is P(X>4) , which does not make sense to me, because if your looking for the probability that there is at least one empty seat, than that must mean that 199 people turned up for their flight and your probability would be the = P (X>1) = 1-P(x<1).

Am I correct or the book is right? If so can you please explain why it is p(x>4) ?

thanks!