1. True False True False True False Starter – True or False
You are equally likely to get a heads or tails when flipping a fair coin
True
False
You are more likely to get an even number when rolling a fair die
The probability of picking a red card is 2/3
True
The probability of landing on a 1 on the spinner is 1/4 2 5 4 3
False
The probability of not picking a black card is 4/6
True
The probability of choosing an ‘A’ from
is 2/10
False

2. Answer: P(Black or Green) = 4 9 + 3 9 = 7 9 The OR rule
Example 1
Rebecca has nine coloured beads in a bag.
Four of the beads are black, two are red and the rest are green.
She removes a bead at random from the bag and notes the colour.
What is the probability she chooses a black bead or a green bead ?
Answer:
P(Black or Green) = = 7 9
The OR rule
For mutually exclusive events;
P( A or B) = P(A) + P(B)

3. Answer: P(Black and black) = 4 9 × 4 9 = 16 81 The AND rule
Example 1
Rebecca has nine coloured beads in a bag.
Four of the beads are black, 2 are red and the rest are green.
She removes a bead at random from the bag and notes the colour before replacing it.
She then chooses a second bead.
What is the probability she chooses a black bead both times?
Answer:
P(Black and black) = 4 9 × 4 9 = 16 81
The AND rule
For independent events;
P( A and B) = P(A) x P(B)

4. Ends of first and second level branches show the different outcomes.
Probability Trees
The probabilities for each event are shown along the arm of each branch and they sum to 1.
Ends of first and second level branches show the different outcomes.

5. Rebecca has nine coloured beads in a bag
Rebecca has nine coloured beads in a bag. Four of the beads are black and the rest are green. She removes a bead at random from the bag and notes the colour before replacing it. She then chooses a second bead.
Draw a tree diagram showing all possible outcomes.
Calculate the probability that Rebecca chooses:
(i) 2 green beads (ii) Two different coloured beads.
First Choice
Second Choice
black
black
green
black
green
green

6. Complete the worksheet.

7. Extension
There are 4 blackcurrant sweets, 3 apple sweets and 4 strawberry sweets in a bowl.
I pick two sweets (And do not replace them).
What is the probability that I pick two sweets of the same flavour?