Logic & puzzles • Classes 9–12
Likely does not mean certain
A fair coin has no memory of your last toss.
Take your time. Speak, draw or write your answers.
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.
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.
After four heads, what is the chance of heads on the next independent fair toss?
KEEP ASKING
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