A probability is a measure of how likely (how

A letter or symbol can be used to represent an event.
For example, let
Please tell us using

*probable*) an event is to happen. Imagine you tossed a coin. What is the probability of the coin landing**Heads**up?## How to Find a Probability

## Question

What is the probability of getting**Heads**in a coin toss?

## Step-by-Step:

## 1

Find the number of ways getting

**Heads**can happen. There is only**1**way of getting**Heads**.## 2

Find the total number of outcomes.
There are

**2**outomes: getting**Heads**and getting**Tails**.## 3

Divide the number of ways of getting

**Heads**(1) (found in**Step 1**) by the total number of outcomes (2) (found in**Step 2**).
Probability of getting heads = 1 ÷ 2 = 0.5

## Answer:

The probability of getting**Heads**is 0.5. Using notation, if**H**is the event of a**Heads**coming up, the probability of the event is**P(H)**. We can also express this as a fraction (½) or a percentage (50%).## A Formula to Find a Probability

The formula for finding a probability is shown below:
$$Probability = \frac{Number~of~ways~an~event~can~happen}{Total~number~of~outcomes}$$

Let's use the formula in an example.
## Question

What is the probability of rolling a 6 on a die?## Step-by-Step:

## 1

Start with the formula.

$$Probability = \frac{Number~of~ways~an~event~can~happen}{Total~number~of~outcomes}$$

## 2

Find the

There is only

*number of ways the event can happen*. Find the number of ways getting a**1**can happen.There is only

**1**way of rolling a**1**.## 3

Find the

*total number of outcomes*. There are**6**outomes: getting**1**,**2**,**3**,**4**,**5**and**6**.## 4

Substitute the

*number of ways the event can happen*and the*total number of outcomes*into the formula.
$$Probability = \frac{1}{6}$$

## Answer:

The probability of rolling a**1**is^{1}⁄_{6}. Using notation, if**1**is the event of rolling a**1**, the probability of the event is**P(1)**. We can also express this as a number (0.167) or a percentage (16.7%).## A Note on Notation

The probability of an event can be written as:*P(Event)*

**H**be the event that a coin lands on**H**eads when it has been tossed. We can denote the probability of getting heads as:*P(H)*

## You might also like...

probabilityunderstanding probabilityunderstanding independent eventsunderstanding the multiplication rule

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