1. Probability Introduction Examples Key words Practice questions Venn diagrams

2. A single number is written on each of six pieces of card One card is selected from the six, the number is recorded and then returned to the set Assuming it is equally likely to pick any card use the results to predict the six numbers Results:

3. Probability With probability we are dealing with the chance of an event happening (or not happening). An event could be anything from ‘obtaining a head when flipping a coin’ to ‘it raining next Thursday’. The probability that an event, A, will happen is written as P(A). The probability that the event A, does not happen is called the complement of A and is written as A' As either A must or must not happen then: P(A') = 1 – P(A)...as probability of a certainty is equal to 1

4. Examples A box contains the numbers 2, 4, 6, 6, 9, 20, 34 A number is picked at random from the box What is the probability it is: (a) Even (b) a multiple of 3 (c) a factor of 18

5. Probability 1 worksheet

6. Key words: Sample / possibility space Outcome Equally likely outcomes Event Complement of an event Mutually exclusive events Addition Law Trial Relative Frequency

7. Venn diagrams In a class of 20 students, 12 study Maths and 13 study English. How many study both subjects?

8. Results so far

9. Probability 2 worksheet

10. Example: When a fair die is rolled find the probability of rolling a 4 or a 1. P(4 or 1) = P(4) + P(1) = 1/6 + 1/6 = 2/6 = 1/3 Handy hint: Exclusive events will involve the words ‘or’, ‘either’ or something which implies ‘or’. Remember ‘OR’ means ‘add’.

11. A box contains 5 red beads and 3 blue beads. Two beads are taken out of the bag. What is the probability of the two beads being the same colour? What is the probability of the beads being different colours?