Probability of mutually exclusive events

Mutually exclusive events

Lesson Objective:

IDENTIFY MUTUALLY EXCLUSIVE EVENTS

CALCULATE PROBABILITIES

Outcomes are mutually exclusive if they cannot happen at the same time

Example: rolling dice once and getting 6 and 2

Multiple Choice

1. When rolling a single die, the events of rolling an even number and rolling a ‘5’ are ...

• Mutually Exclusive

• Not Mutually Exclusive

Multiple Choice

3. When rolling a single die, the events of rolling an even and an odd number are ...

• Mutually Exclusive

• Not Mutually Exclusive

Multiple Choice

4. If a spinner is numbered 1 – 8, when you spin it the events of spinning an even number and a number less than 4 are ...

• Mutually Exclusive

• Not Mutually Exclusive

Multiple Choice

5. Rolling an odd number and rolling an even number on a normal six-sided die are

• Mutually exclusive

• Not mutually exclusive

If a set of mutually exclusive events covers all possible outcomes then their sum of probabilities is 1

Example: Arif throws a biased coin. The probability of getting tails is 0.7. Therefore, the probability of getting heads is 1-0.7=0.3

Mutually Exclusive Events

When two events CANNOT happen at the same time, the events are said to be MUTUALLY EXCLUSIVE.

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An example of this is getting heads on a coin and a tail on the same coin in the same toss.

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Another example would be getting a six on a regular die and a five on the same die in the same roll.

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A pre-Covid example would be being at school and being at home at the same time.

If a set of mutually exclusive events covers all possible outcomes then their sum of probabilities is 1.

Example: Arif throws a biased coin. The probability of getting tails is 0.7. Therefore, the probability of getting heads is 1 - 0.7 = 0.3

Multiple Choice

Said throws a biased coin. The probability of getting tails is 0.4.

Work out the probability of getting heads.

• 0.4

• 0.6

• 0.8

• 0.2

Multiple Choice

Laman plants a daffodil bulb. The probability that the bulb will grow is 0.8.

What is the probability that the bulb will not grow?

• 0.8

• 0.2

• 0.6

• 0.4

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