Logic & puzzles • Classes 9–12

Likely does not mean certain

A fair coin has no memory of your last toss.

About 12 minutes Read · try · explain

Take your time. Speak, draw or write your answers.

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01 / UNDERSTAND

Here is what is happening.

For independent tosses of a fair coin, each toss has probability 1/2 of heads. Previous results do not force the next one. Experimental proportions can differ from theoretical probability, particularly with few trials.

Pause. Make the idea your own.

Explain one idea to a partner, draw it or write it in your own words. Which part is an observation, an example or a question?

You can use a home language. No need to share personal experiences or finish everything in one sitting.

02 / MAKE IT YOUR OWN

Your little investigation

What you need

Paper. Use the imagined sequence H, H, H, H; no gambling or purchases.

List the possible outcomes of two fair tosses: HH, HT, TH, TT.
Count outcomes with exactly one head.
Explain why four previous heads do not guarantee tails next.

03 / CHECK YOUR UNDERSTANDING

After four heads, what is the chance of heads on the next independent fair toss?

01/21

KEEP ASKING

Another question is waiting.

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