PROBABILITY

In general:
Probability of an event happening = Number of ways it can happen/Total number of outcomes

Example

The chances of rolling a "4" with a die

Number of ways it can happen: 1 (there is only 1 face with a "4" on it)

Total number of outcomes: 6 (there are 6 faces altogether)

So the probability = 1/ 6

There are 5 marbles in a bag: 4 are blue, and 1 is red. What is the probability that a blue marble gets picked?

Number of ways it can happen: 4 (there are 4 blues)

Total number of outcomes: 5 (there are 5 marbles in total)

So the probability = 4/5 = 0.8

Probability Line

We can show probability on a Probability Line:

Probability is always between 0 and 1

References:

https://www.mathsisfun.com/data/probability.html

https://www.youtube.com/watch?v=uzkc-qNVoOk