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Counting and Basic Probability · Question 53 of 65

Question 53

EasyOriginal question

Three fair coins are tossed at the same time. What is the probability of getting exactly two heads?

Options for question 53

Show the answer and explanation
CorrectNot quiteAnswer A

Correct answer: A

Explanation

  1. Three coins give 23=82^3 = 8 equally likely outcomes.

  2. Exactly two heads: HHT, HTH, THH, which is 3 outcomes.

  3. Probability =38= \frac{3}{8}.

Worth noting

12\frac{1}{2} is P(at least two heads), which also counts HHH. 78\frac{7}{8} is P(at least one head), and 23\frac{2}{3} wrongly divides 2 heads by 3 coins.

Concept
Listing outcomes for three coins
Typical time
40 s
Your time
—
The rule this testsCoins, dice and cards
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