A-level · Statistical distributions

Approximating a binomial with a normalExam-style questions

When n is large and p not too extreme, approximating B(n, p) by N(np, np(1−p)) — and applying the continuity correction (±0.5) when moving from the discrete binomial to the continuous normal.

Start practising Read the lesson

16 questions · A-level level · mark scheme and worked solution on each · no sign-up to try

DifficultyAll Level 3 Level 4 Level 5

1
The probability that a randomly chosen visitor to a particular museum buys a guidebook is $0.24$ .
(a) Use a suitable approximation to find the probability that, of $150$ randomly chosen visitors, more than $40$ buy a guidebook.

(4 marks)
(b) Justify your use of the approximation in part (a).

(1 mark)
(c) Find the probability that, of $12$ randomly chosen visitors, at least $3$ buy a guidebook.

(3 marks)
Level 4 · 8 marksTry it