Real-life situations can teach us a lot about the rules of probability, which is all about chance. Let’s make it easier to understand with some fun examples!

Addition Rule

The addition rule is helpful when we want to know the chance of either one of two events happening.

Imagine you have a bag with 3 red marbles and 2 blue marbles. If you want to find out the chance of drawing a red marble or a blue marble, you can just add the chances together:

• Chance of red: ( P(R) = \frac{3}{5} )
• Chance of blue: ( P(B) = \frac{2}{5} )

Using the addition rule, we can find the total chance like this:

[ P(R \text{ or } B) = P(R) + P(B) = \frac{3}{5} + \frac{2}{5} = 1 ]

This means that if you pick a marble, you are sure to get either a red or a blue one!

Multiplication Rule

Now, let’s look at the multiplication rule, which we use for events that don’t affect each other.

For example, if you flip a coin and roll a dice, what’s the chance of landing on heads and rolling a 4?

• Chance of heads: ( P(H) = \frac{1}{2} )
• Chance of rolling a 4: ( P(4) = \frac{1}{6} )

Using the multiplication rule, we can calculate:

[ P(H \text{ and } 4) = P(H) \times P(4) = \frac{1}{2} \times \frac{1}{6} = \frac{1}{12} ]

These examples show how we can use the addition and multiplication rules in real life. Probability can be both fun and useful!