M3.7.8 For the adult

Experiments and fair games

I tossed a coin 50 times. Why did I not get exactly 25 heads?

What this chapter teaches

Real results are near what probability expects, but not exactly equal. More trials usually come closer. A game is fair when every player has the same chance of winning, which you find by counting outcomes.

Three questions to ask

There is no one right wording. Listen for the idea.

  1. About how many heads do you expect in 40 tosses of a fair coin?
  2. Why is a run of 10 tosses a weaker guide than a run of 100?
  3. How could you check whether a dice game is fair, without playing it?

After the chapter, the learner can

  • Toss a coin 50 times and compare with what you expected
  • Decide if a dice game is fair

What they copy into their notebook

Expect about half heads from a fair coin, but results vary a little. More tosses usually come closer. A game is fair when each player has the same chance. Count the winning outcomes.

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