What random means
Show on a big screenA coin spins before every cricket match. No one can call it for sure. To call a toss is to name its result before it lands.
Nobody calls the next one
Random — a result nobody can name before it happens. A toss is random. You know the possible results: heads or tails. You cannot say which one will come.
The past tosses do not help. A fair coin is equally likely to show heads or tails. For a fair coin, ten heads in a row change nothing. Each toss is separate from the earlier ones. So the next toss is as uncertain as the first.
A whole run can be described
One toss cannot be called. A long run can be described. A run is many tosses in a row. "About half were heads" is a real claim for a fair coin. You can check it.
| Call number | Called | Coin landed | Right? |
|---|---|---|---|
| 1 | heads | heads | yes |
| 2 | heads | tails | no |
| 3 | tails | tails | yes |
| 4 | heads | heads | yes |
| 5 | tails | heads | no |
| 6 | tails | tails | yes |
Four of six calls were right this time. With a fair coin, no way of calling beats half right. That holds over a long run.
Rule: The next toss cannot be called. A whole run can be described.
Call each toss. See how you score.
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Try the lab to finish this lesson.