Mathematics 9709 · AS & A Level · The normal distribution
The normal distribution — practice question
At a company call centre, $90\%$ of callers are put through straight away to a representative. A random sample of $12$ callers is selected.
(a)[3]
Determine the probability that fewer than $10$ of these callers are connected straight away.
(b)[5]
A random sample of 80 callers is selected. Use an approximation to determine the probability that more than 69 of these callers are connected straight away.
(c)[1]
Justify why your approximation is used in part (b).
Worked solution & mark scheme
This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: “By using binomial probabilities such as $1-P(X=10)-P(X=11)-P(X=12)$” …