Two fair coins are flipped simultaneously. What is the probability of obtaining at least one Head?
Answer and explanation
Correct answer: A. 3/4
- Step 1: Sample space of two coin flips: S = {HH, HT, TH, TT}, total 4 equally likely outcomes. Step 2. Outcomes with at least one head: {HH, HT, TH}, exactly 3 outcomes. Probability = 3/4. Answer: 3/4. Why not the others: 1/2 is probability of exactly one head; 1/4 is probability of both heads (or both tails); 2/3 uses wrong sample space.
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