Lesson Notes By Weeks and Term v4 - JHS 2

Lesson Video

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Performance objectives

• Define probability and its importance.
• Identify the total number of possible outcomes.
• Calculate the probability of an event as a fraction.
• Compare probabilities of different events.
• Solve practical problems involving probability.

Lesson summary

This lesson introduces the fundamental concept of probability, which is the mathematical way of measuring how likely something is to happen. In our daily lives in Ghana, we often talk about chance. For example, what is the chance that it will rain in Accra today? What is the chance that the Black Stars will win their next match? Or even in a simple game of Ludo, what is the chance of getting a '6' to start? Probability gives us a way to measure these chances using numbers, specifically fractions. Understanding probability helps us make smarter decisions based on how likely different outcomes are.

Lesson notes

This section breaks down the important ideas you need to understand probability. A. What is Probability?

Probability is a number that tells us how likely an event is to occur. It is always a value between 0 and 1. A probability of 0 means the event is impossible. (e.g., The probability of the sun rising from the west is 0). A probability of 1 means the event is certain. (e.g., The probability that the sun will rise tomorrow is 1). Probabilities between 0 and 1 tell us how likely the event is. A probability closer to 1 is very likely, and a probability closer to 0 is very unlikely. B. Key Terminology

To calculate probability, we must first understand these words: Experiment: Any action or process where the result is uncertain. *Examples:* Tossing a coin, rolling a die, picking a ball from a bag without looking. Outcome: A single possible result of an experiment. *Examples:* When tossing a coin, one outcome is 'Heads'. When rolling a die, one outcome is '4'. Sample Space (S): The set of *all possible outcomes* of an experiment. We usually write this in curly braces { }. *Example 1:* For tossing a coin, the Sample Space S = {Head, Tail}. The total number of outcomes is 2. *Example 2:* For rolling a standard six-sided die, the Sample Space S = {1, 2, 3, 4, 5, 6}. The total number of outcomes is 6. Event (E): The specific outcome or group of outcomes that we are interested in. *Example:* In rolling a die, the event we might be interested in is 'getting an even number'. The outcomes for this event would be {2, 4, 6}. C. The Formula for Probability

The main goal of this lesson is to calculate probability and write it as a fraction. We use a simple formula: