Probability

Probability

In this chapter, you will learn about probability, how to find the chance of an event happening, and how to solve problems using probability. By the end of this chapter, you will be able to calculate simple probabilities and understand their use in real life.

Key Concepts

• Probability: The measure of how likely an event is to happen.
• Experiment: An action or process that leads to one or more outcomes.
• Outcome: A possible result of an experiment.
• Event: One or more outcomes of an experiment.

What is Probability?

Probability tells us how likely something is to happen. It is written as a number between 0 and 1.

• 0 means impossible (cannot happen).
• 1 means certain (will definitely happen).
• A probability between 0 and 1 means it may or may not happen.

Formula for Probability

Probability of an event = Number of favourable outcomes / Total number of possible outcomes

Example: If you toss a coin, there are 2 possible outcomes: Heads or Tails.
Probability of getting Heads = 1/2

Examples

• Rolling a die: Probability of getting a 3 = 1/6 (since there are 6 faces).
• Picking a red ball from a bag with 3 red and 2 blue balls: Probability = 3/5.

Properties and Applications

• Probability is always between 0 and 1.
• The sum of probabilities of all possible outcomes is 1.
• Probability helps in predicting outcomes in games, weather, and many real-life situations.

Practice Questions

1. What is the probability of getting a 5 when rolling a die?
2. A bag has 4 green and 6 yellow balls. What is the probability of picking a green ball?
3. If you toss a coin, what is the probability of getting tails?
4. What is the probability of picking a vowel from the letters A, B, C, D, E?
5. Can the probability of an event be greater than 1?

Challenge Yourself

• A box has 5 red, 3 blue, and 2 green balls. What is the probability of picking a blue ball?
• If you roll two dice, what is the probability of getting a total of 7?

Did You Know?

• Probability is used in weather forecasting, sports, and even in insurance!
• The word "probability" comes from the Latin word "probabilis," meaning "likely."

Glossary

• Probability: The chance of something happening.
• Outcome: The result of an experiment.
• Event: One or more outcomes.
• Experiment: An action that leads to outcomes.

Answers to Practice Questions

1. 1/6
2. 4/10 or 2/5
3. 1/2
4. 2/5 (A and E are vowels)
5. No, probability is always between 0 and 1.

---

Practice probability problems to understand how chance works in real life!