1. STARTER
The probability that a particular page in a maths book has a misprint is Find the probability that of 12 pages in the book:
4 of them have a misprint
n = 12 and p = 0.2
P(X = 4) = 0.133
Fewer than 2 of them contain a misprint.
P(X < 2) = =

2. STARTER If X ≈ B (n, 0.6) and P (X< 1) = 0.0256, find n
Therefore P(X = 0) =
= nC0 (0.6)0 (0.4)n
= 1 x 1 x (0.4)n
0.4n =
n = (Solver or by taking
logs each side)

3. Note 5: Expected Value of a Binomial Distribution
For the binomial distribution where
the expectation of X (or mean of X) is
E(X) = np

4. Example: A farmer plants 150 gum trees, each of which have an individual probability of surviving the winter conditions of 0.8. Find the expected number that survive the winter. E(X) = np
= 150 × 0.8
= 120

5. New Book
Page 535
Exercise 15E and F