Introduction to Games of Chance
Primary 4 · Mathematics
Introduction to Games of Chance
Lesson 4 of 4
30 min
Let's begin
Mugisha and his friends are playing Ludo. He needs a 6 to move his first counter out. "I never get a six!" he complains, after three throws. Is 6 really harder to get than the other numbers?
A die (two or more are called dice) is a cube with 6 faces. The faces show 1, 2, 3, 4, 5 and 6 dots.
Fun fact: on an ordinary die, the dots on opposite faces always add up to 7 (1 and 6, 2 and 5, 3 and 4).
When you throw a fair die, there are 6 equally likely outcomes. So the chance of any one number is 1 out of 6, which we can write as 16. A 6 is no harder to get than a 1 or a 3. Mugisha was just unlucky!
To find a chance, count the outcomes that match, out of all 6.
| Event | Outcomes that match | Chance |
|---|---|---|
| An even number | 2, 4, 6 | 3 out of 6 |
| A number greater than 4 | 5, 6 | 2 out of 6 |
| A number less than 7 | 1, 2, 3, 4, 5, 6 | 6 out of 6: certain |
| A 7 | none | 0 out of 6: impossible |
Throw a die 30 times and tally each number. Each number should come up about 5 times, because 30 ÷ 6 = 5. It will not be exactly 5 for each, and that is how chance works.
Tip
Chance = matching outcomes out of all outcomes. For one die there are always 6 outcomes, so count how many of the 6 match.
Work each one in your exercise book first. Then tap Show answer to check.
What is the chance of throwing a 3 with one die?
Answer: 1 out of 6.
What is the chance of throwing a number greater than 2?
Answer: 4 out of 6 (3, 4, 5 and 6).
Is throwing a number less than 6 likely or unlikely?
Answer: Likely. 5 of the 6 outcomes are less than 6.
Gatete wins with 1 or 2. Ishimwe wins with 5 or 6. On 3 or 4 they throw again. Is the game fair?
Answer: Yes. Each boy has 2 winning outcomes.
Which number is opposite the 2 on an ordinary die?
Answer: 5, because opposite faces add up to 7.
What you learned today
Sources and credits
The Ludo story, the die games and the die picture were written by Ganzaa. The stories, Rwandan examples, diagrams and practice questions were written by Ganzaa.
Quick check
What is the chance of throwing an odd number with one die?
