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jmc

counting and probability senior

Problem

8 coins are simultaneously flipped. What is the probability that heads are showing on at most 2 of them?
Solution
The number of ways for the outcome to have exactly 0, 1, or 2 heads are , , or , respectively. There are total possible outcomes (2 possibilities for each coin, and 8 coins). So the answer is .
Final answer
\dfrac{37}{256}