What do you remember about probability?

In this activity, we will look at a mix of probability questions - similar to ones you have seen in the past!

Here is a recap of what we've learnt about **probability**:

**Probability **is calculated by dividing the number of **desired outcomes** (what we are finding the probability of) by the number of all **possible outcomes**.

For example, the probability of getting heads on a fair coin is P(H) = 1/2 because there is 1 side with heads on it out of 2 possible sides it can land on!

We can write probability as a **fraction**, **decimal **or **percentage**.

So, the our probability of getting heads is P(H) = 1/2 = 0.5 = 50%

Unless the question specifies what form the answer should be, you can choose whichever one you are most comfortable with!

The **probability of something not happening** is 1 minus the the probability of it happening.

For example, the probability of getting a 5 on a fair die is 1/6.

So the probability of *not *getting a 5 is: 1 - 1/6 = 5/6

Finally, any time we want to calculate the probability of event A **or **event B happening, we **add **their respective probabilities:

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

For example, the probability of throwing a 2 **or** a 5 on a six-sided die is:

P(getting a 2 or a 5) = P(getting a 2) + P(getting a 5) = 1/6 + 1/6 = **2/6**

Similarly, any time we want to calculate the probability of event A **and **event B happening, we **multiply **their respective probabilities:

**P(A and B) = P(A) x P(B)**

For example, the probability of getting a heads on a coin and a 4 on a six-sided die is:

P(getting heads and a 4) = P(heads) x P(getting a 4) = 1/2 × 1/6 = 1/12

Phew - there's a lot to remember there! You can look back at this introduction at any point by clicking on the red help button on the screen.

Let's have a go at some questions!