Probability of two events

Example

A coin is tossed twice. Draw a probability sample space

diagram showing all the possible outcomes.

What is the probability of the two tosses giving two heads?

Example

Two dice are thrown together.

a) List all possible outcomes

b) Use your list to find the probability that

(i) the sum of the scores on the dice is 5

(ii) the sum of the scores is even.

(iii) the sum of the scores is a prime number.

Example

When the two spinners are spun, what is the probability of

getting a B on the first and a 3 on the second?

Example

A penny and a die are thrown together.

a) How many possible outcomes are there?

b) What is the probability of getting a head?

c) What is the probability of getting a six?

d) What is the probability of getting a head and a

six?

Example

Two bags each contain a number of marbles. The first bag

has 2 blue and 2 green and the second bag has 1 green

and 3 blue.

One marble is drawn at random from each bag.

a) Draw up a list of all possible outcomes

b) Find the probability that one marble is blue and the

other is green.

Example

I have four coins in my left pocket: They are 2p, 5p, 5p and 10p. I

have three coins in my right pocket: they are 2p, 5p and 20p.

Two coins are chosen at random, one from each pocket.

a) Draw up a list of all possible sums of money for these two

coins.

b) Find the probability that:

(i) coins are 5p

(ii) the total value of the coins is 7p.