What is the chance the sun will rise tomorrow?

How likely is it that you'll get tails when you flip a fair coin?

How likely is it that a die will land on 7?

Did you notice that some scenarios are much more likely to happen, while some might be absolutely certain and others impossible?

The sun will 100% rise tomorrow.

When something is **certain** to happen, it has a probability of **1**.

*(Makes sense as 100% is 1 when converted from percentages!)*

There are two possible outcomes on a coin (heads and tails) - so the probability of getting tails is 1/2.

If something is **just as likely to happen as not** (even chance), it has a probability of **½** that it will happen.

There is no 7 on a die so there is 0 chance that we will get a 7 when we roll it.

If something is **impossible**, it has a probability of **0** that it will happen.

Probability therefore can be only numbers between 0 and 1 - you can't get any less of a chance than impossible and any more of a chance than certain!

We often visualise it using a probability scale:

Let's have a go at some questions!