Problem-Solving and Data AnalysisMediumProbability of two independent events
Problem-Solving and Data Analysis practice question
A fair coin is flipped twice. What is the probability that both flips land heads?
- A. 1/4Correct
- B. 1/2
- C. 1/3
- D. 3/4
Answer: A. 1/4
The flips are independent, so multiply: (1/2) × (1/2) = 1/4. Equivalently, of the four equally likely outcomes HH, HT, TH, TT, only one is both heads.
Why the other answers are wrong
- B. 1/2
- 1/2 is the probability of heads on ONE flip. For two heads in a row, the probabilities multiply.
- C. 1/3
- There are four equally likely outcomes, not three — HT and TH are different outcomes.
- D. 3/4
- 3/4 is the probability of getting at LEAST one tail, the opposite event.
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