Chapter 17 - The binomial distribution

Question 1

Conditions of the trial

Answer 1

• conducting trials on random samples of a certain size, denoted by n
• two possible outcomes (success, denoted by p, and failure, denoted by q)
• both outcomes have fixed probabilities, the two adding to 1, so p + q = 1
• P(success) is independent of previous trials

Question 2

The expectation of B(n, p)

Answer 2

Mean can be calculated by:
- multiplying each probability by the total to get the frequency
- multiplying each frequency by the number of successes
- Adding these numbers together
- Dividing by the total

Question 3

nPr

Answer 3

When order DOES matter, so for e.g. GSG is different to GGS and SGG; = n!/(n-r)!

Question 4

nCr

Answer 4

When order DOESN’T matter, so for e.g. GSG is the same as GGS and SGG; = n!/r!(n-r)!