Lesson 3: Introduction to Probability – Basic Concepts and Simple Problems

🎲 b. Rolling a Die

Possible outcomes: 1, 2, 3, 4, 5, 6

🎡 c. Spinning a Spinner

If a spinner is divided equally into Red, Green, Yellow, and Blue,
each outcome has a 1 in 4 chance.

💬 4. Words Used to Describe Probability

We often describe probability using words, especially when we don’t know the exact number.

🔍 Sample Problem Walkthroughs

✅ Example 1: Rolling an Even Number

Question: What is the probability of rolling an even number (2, 4, or 6) on a fair die?

Solution:

• Favorable outcomes = 3 (2, 4, 6)
• Total outcomes = 6

✅ Example 2: Picking a Red Ball

Question: A bag contains 5 red and 3 blue balls. What is the probability of picking a red ball?

• Favorable = 5
• Total = 5 + 3 = 8

✅ Example 3: Certain and Impossible Events

• Getting a number less than 7 on a die = Certain
• Getting a 9 on a die = Impossible

📊 Practice Exercises

Part A: Short Answer

1. What is the probability of tossing a tail?
2. What is the probability of rolling a 5?
3. A box has 4 white and 1 black marble. What is the probability of picking a white one?

Part B: True or False?

1. The probability of rolling a 7 on a die is 0.
2. The probability of flipping a coin and getting a head is 1.
3. The probability of picking a red ball from a bag that has only red balls is 1.

Part C: Match the Event to the Word

📝 Answers and Explanations

Part A:

Part B:

1. True
2. False (P = 0.5)
3. True

Part C:

• Heads on coin → Even chance
• 10 on die → Impossible
• Rain → Likely
• Sunrise → Certain

✅ Recap

In this lesson, you learned what probability means, how to calculate it using a simple formula, and how to describe the likelihood of events using both numbers and words.
We explored common examples like coins, dice, spinners, and real-life situations.

💭 Reflection Prompt

Think of a simple event in your daily life — like picking a color from your pencil case or spinning a bottle.
Can you list all the possible outcomes?
Can you describe the chance of each outcome using a fraction?