# Mutually exclusive

Time – can’t both happen (at the same time)

Two **mutants** (mutually) are **excluded** (excluded) from entering the club together by **time**.

Mutually exclusive is about time. The event can’t happen at the same time.

E.g. you can’t have both 1 and 2 children. Throwing a dice and obtaining a 6 and a 1 are mutually exclusive. You can’t be 170cm and 180cm tall.

**Example 1**

If you roll a dice, what is the probability of rolling a 3 or rolling an even number? (This is a mutually exclusive example.)

`Remember\ probability\=(N\umber\ of\ RIGHT\ answers)/(N\umber\ of \ALL\ possibl\e\ answers`

Start by drawing a probability tree:

Now add the probabilities up the column.

`1/6+1/6+1/6+1/6=(1+1+1+1)/6=4/6=2/3`

**Answer:**

The probability of rolling a dice and getting a three or an even number is 2 in 3 or = 0.67.

And if 1 = 100% then 0.67 = 67% chance.

**Example 2**

What is the probability of you picking a heart from a pack of cards?

`Remember\ probability\=(N\umber\ of\ RIGHT\ answers)/(N\umber\ of \ALL\ possibl\e\ answers`

For 1 card probability = `1/52`

Start by drawing a probability tree:

`1/52+1/52+1/52+1/52+1/52+1/52+1/52+1/52+1/52+1/52+1/52+1/52+1/52=13/52`

**Answer: **

The probability of picking a heart from a pack of cards = `13/52=1/4`

1 in 4 chance or 0.25.

And if 1 = 100% then 0.25 = 25% chance.