INDEPENDENT EVENTS

Events are independent if the outcome of one event does not affect the outcome of another. For example, if you throw a die and a coin, the number on the die does not affect whether the result you get on the coin.

If A and B are independent events, then the probability of A happening AND the probability of B happening is P(A) × P(B).

P(A and B) = P(A) × P(B)

Example:

If a dice is thrown twice, find the probability of getting two 5’s.

Solution:

Example:

Two sets of cards with a letter on each card as follows are placed into separate bags.

Sara randomly picked one card from each bag. Find the probability that:

a) She picked the letters ‘J’ and ‘R’.

b) Both letters are ‘L’.

c) Both letters are vowels.

Solution:

a) Probability that she picked J and R =

b) Probability that both letters are L =

c) Probability that both letters are vowels =

Example:

Two fair dice, one coloured white and one coloured red, are thrown. Find the probability that:

a) the score on the red die is 2 and white die is 5.

b) the score on the white die is 1 and red die is even.

Solution:

a) Probability the red die shows 2 and white die 5 =

b) Probability the white die shows 1 and red die shows an even number =

The following videos give more examples of calculating the Probability of Independent Events.

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