A-level · Statistical distributions

Calculating binomial probabilities P(X = r)Exam-style questions

The binomial probability formula P(X = r) = nCr · p^r · (1−p)^(n−r), why it has that shape (choose which r of the n trials succeed, then multiply the success and failure probabilities), how to evaluate it including the special cases r = 0 and r = n, and how it matches the binompdf function on a calculator.

Start practising Read the lesson

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

DifficultyAll Level 2 Level 3 Level 4 Level 5

1
$X \sim B(12, 0.25)$ . Find $P(X = 3)$ , to 4 d.p.
Level 2 · 2 marksTry it
2
$X \sim B(15, 0.4)$ . Find $P(X = 6)$ , to 4 d.p.
Level 2 · 2 marksTry it