The big ideaOdds are counted, and a wheel with one winning slot in ten favours its keeper.
How it works
At the fair, Mr. Odd's Lucky Wheel has ten equal slots: nine plain and one gold. One coin buys a spin, and gold pays six coins back.
Counting the slots gives the odds: one gold slot out of ten is one chance in ten to win.
On average, ten spins put in ten coins and give back six, so the stall keeps four. Whoever runs a game like this is called the house.
A short run can look different, but over many turns the house keeps more than it pays out. Odds decide the long run, not luck. It is not a way to get money.
Fifty spins: the stall keeps twenty.Two wheels.
Example 1: Counting the odds
The wheel has 10 equal slots, and 1 is gold.
One gold slot out of ten is one chance in ten.
Example 2: Ten spins
10 spins cost 10 coins.
On average 1 spin in 10 lands on gold and pays 6 coins.
10 − 6 = 4
The stall keeps 4 coins.
Example 3: A hundred spins
100 spins cost 100 coins.
About 10 spins land on gold, and each pays 6 coins: 10 × 6 = 60
100 − 60 = 40
The stall keeps 40 coins.
Example 4: The second wheel
It has five slots, one gold, and gold pays 4 coins.
5 spins cost 5 coins, and on average 4 come back.
5 − 4 = 1
The stall still keeps 1 coin in every 5.
Words to know
odds
Gold slots out of all slots: how many chances to win.
house
Whoever runs the game.
on average
What happens over many turns, not on one.
slot
One equal part of the wheel.
Watch out
Each spin starts fresh. A win does not change the odds.
A short lucky run is luck. It does not mean the odds changed.
More spins make the stall keep more, never less.
Places have rules about who may play games like this, so ask a grown-up.
Try it
A wheel has 20 equal slots and 1 gold. What are the odds of gold?
Ten spins put in 10 coins and give back 6. How many coins does the stall keep?
Kit wins on his first spin. Is the next spin more likely to win?
Over many turns, who keeps more: the player or the house?
Answers: 1. One in twenty · 2. 4 · 3. No · 4. The house
Try at homeWith a grown-up, talk about games where you put in coins and might get some back. Ask what rules your place has about them, and count the odds together on the pretend wheel.
For grown-upsThis is about counting chances on a pretend wheel, never about playing. Count the slots together and talk about why a game built this way is not a way to get money. Ask what rules your place has about games with coins.
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