Introduction to Games of Chance
Primary 4 · Mathematics
Introduction to Games of Chance
Lesson 3 of 4
30 min
Let's begin
At a family gathering, Uwase's uncle takes out a pack of playing cards. He shuffles them well. "Pick one card without looking," he says. "If it is red, you get a point. If it is black, I get a point." We play for points and for fun, never for money.
Is the uncle's game fair? First, let's find out what is in a pack.
A full pack (without jokers) has 52 cards. They are split into 4 suits:
When the pack is shuffled and you pick without looking, every card has the same chance. So:
Uwase wins with 26 red cards and her uncle wins with 26 black cards. The numbers are equal, so the game is fair.
What if Uwase wins only with a heart, and her uncle wins with any other card? Then Uwase has 13 winning cards and her uncle has 39. That game is not fair.
Write the numbers 1 to 10 on ten cards, mix them and pick one.
Tip
Count the winning cards for each player. Same number of cards = same chance = a fair game.
Work each one in your exercise book first. Then tap Show answer to check.
How many red cards are in a full pack?
Answer: 26.
How many picture cards (jacks, queens and kings) are in a full pack?
Answer: 12, because each of the 4 suits has 3 picture cards.
You pick a card from a full pack. Which is more likely: a spade, or a black card?
Answer: A black card: there are 26 black cards but only 13 spades.
With the ten number cards 1 to 10, what is the chance of picking a 10?
Answer: 1 out of 10.
Keza wins with the cards 1, 2 and 3. Mutesi wins with 4, 5, 6, 7, 8, 9 and 10. How can you make the game fair?
Answer: Give each girl 5 cards, for example Keza wins with 1 to 5 and Mutesi wins with 6 to 10.
What you learned today
Sources and credits
The facts about the pack, the card games and the card pictures were written by Ganzaa. The stories, Rwandan examples, diagrams and practice questions were written by Ganzaa.
Quick check
How many cards are in a full pack without jokers?
