In this lesson:
By the end of this lesson, you should be able to:
Five friends want one concert ticket.
What counts as a fair way to decide who gets it?
A procedure is fair when every option has the same probability of being chosen.
A trick coin lands heads 70% of the time. You assign Ana heads, Ben tails.
It uses chance — but is it fair? Decide before advancing.
The trick coin is random but not fair — Ana gets , Ben gets .
Other unfair methods: alphabetical, seniority, first to ask.
Which give equal probability?
You can now test any procedure for fairness.
Next: construct one — split a device's equally likely outcomes into equal blocks, one per choice.
Assign two faces each: 1-2, 3-4, 5-6 — every person gets .
Faces 1-2-3 / 4-5 / 6 give — not equal, so not fair.
You have one six-sided die and two people, Lee and Sam.
Design a fair procedure and state each person's probability.
Build equal blocks before advancing.
For lots to be fair:
✓ Fair = equal probability — not merely "random"
✓ Build it by splitting outcomes into equal blocks
✓ A fair device with unequal blocks is still unfair
Computers pick fairly with random number generators — integers in a range.
Next lesson: mapping that range to choices, and the bias when the count doesn't divide evenly.