IXL | Probability of either one event or another event occurring

You flip a coin.

What is P(heads or tails)?

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Learn with an example

question

You pick a card at random.

What is P(5 or even)?

key idea

Mutually exclusive events can never occur at the same time. If A and B are mutually exclusive, then:

P(A or B) = P(A) + P(B)

solution

The events 5 and even are mutually exclusive. It's impossible for one of these cards to be both at the same time.

Find P(5). There are 3 cards, numbered 4, 5, and 6.

P(5)

Find P(even). The even numbers are 4 and 6. There are 2 even numbers.

P(even)

Find P(5 or even).

P(5 or even)

= P(5) + P(even)

Write your answer in simplest form.

P(5 or even) = 1

Looking for more? Try this:

Lesson: Compound probability

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Teacher tools

Work it out

Not feeling ready yet? These can help:

G.1Add and subtract fractions

II.8Make predictions using theoretical probability

Lesson: Compound probability

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