Chapter 16 - Probability

Question 1

Probability (chance)

Answer 1

Way of describing the likelihood of different possible outcomes occurring as a result of some experiment

Question 2

Trial

Answer 2

Another word for experiment; used to describe the binomial situation where there are just two possible outcomes

Question 3

Event

Answer 3

Describes several outcomes put together e.g. a die lands on an even number has three possible outcomes; can also describe a single outcome

Question 4

Expectation (expected frequency)

Answer 4

Given by np, where n is the population size and p the probability

Question 5

Mutually exclusive

Answer 5

P(A U B) = P(A) + P(B) as there is no overlap between the two Venn circles

Question 6

Independent (not mutually exclusive)

Answer 6

P(A U B) = P(A) + P(B) - P(A n B) as there is an overlap between the Venn circles, so this must be done to prevent including doubles

Question 7

Sample space diagram

Answer 7

Can show all the possible outcomes; makes it hard to miss out possible outcomes

Question 8

Tree diagram

Answer 8

Alternative to sample space diagram to reduce writing; can find combined probabilities by multiplying along the branches

Question 9

Probability distributions

Answer 9

• ‘The random variable _____ is denoted by X and the possible values it can take by x.’
• sum of P(X=x) = 1
• E(x) expectation or mean = sum of x * P(X=x)

Question 10

Discrete uniform distribution

Answer 10

All possible values of the variable have the same probability