Free Practice Question
PS · Problem Solving
705-805
Probability
If a fair coin is flipped four times, what is the probability of obtaining 'tails' no more than once in the four flips?
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Official Explanation
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To determine the probability of obtaining 'tails' no more than once when a fair coin is flipped four times, follow these steps:
Total Possible Outcomes:
Each coin flip has 2 possible outcomes: heads (H) or tails (T). For four flips, the total number of possible outcomes is:
Desired Outcomes:
We want the number of outcomes where 'tails' appears no more than once. This includes:
- 0 tails: All four flips are heads (HHHH).
- 1 tail: One flip is tails and the other three are heads. The tail can occur in any one of the four positions (THHH, HTHH, HHTH, HHHT).…
Each coin flip has 2 possible outcomes: heads (H) or tails (T). For four flips, the total number of possible outcomes is:
We want the number of outcomes where 'tails' appears no more than once. This includes:
- 0 tails: All four flips are heads (HHHH).
- 1 tail: One flip is tails and the other three are heads. The tail can occur in any one of the four positions (THHH, HTHH, HHTH, HHHT).…
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What it tests
Your ability to compute probabilities of single and compound events, including 'at least one' questions.
Common trap
Forgetting to use the complement for 'at least one', or treating dependent events as independent.
Details
Difficulty
705-805
Type
PS
Category