Calculating probabilities can be tricky for Year 8 students.

Sometimes, students have a hard time telling the difference between simple events, like flipping a coin, and compound events, like rolling two dice. This confusion can make it tough to know which rules to use.

Let's break down the two main rules of probability:

1. Addition Rule: Use this rule when you're looking at the chance of either event happening.

   A big mistake students make is forgetting about events that overlap. This can lead to wrong answers.

   • Formula: If events A and B cannot happen at the same time (this is called mutually exclusive), then: $P(A \text{ or } B) = P(A) + P(B)$ This means you just add the probabilities of both events.

2. Multiplication Rule: This rule comes into play when you're dealing with independent events—events that don't affect each other.

   Sometimes students forget to check if events are independent, which can cause problems in their calculations.

   • Formula: For independent events A and B: $P(A \text{ and } B) = P(A) \times P(B)$ Here, you multiply the probabilities of both events.

To help you get better at this, practice with clear examples. Don’t hesitate to ask questions about the different types of events. This will make things a lot easier to understand!