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Probability of getting at least one head when flipping 3 coins:

A7/8 (= 1 - P(no heads) = 1 - 1/8)
B1/8
C1/2
D3/8
Answer & Solution
Correct answer: A. 7/8 (= 1 - P(no heads) = 1 - 1/8)
Complementary approach: P(no heads) = (1/2)³ = 1/8. P(at least one H) = 1 - 1/8 = 7/8. Faster than enumerating cases.
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