A bag holds 5 red and 3 blue marbles. Two marbles are drawn without replacement. What is the probability that both are red?
Answer and explanation
Correct answer: C. 5/14
- Step 1: The first draw is red with probability 5/8.
- Step 2: Then 4 red remain among 7, so the second is red with probability 4/7.
- Step 3: Multiply: 5/14.
Answer
5/14.
Why not the others: 25/64: the first marble was assumed to be replaced. 29/40: the probabilities were added instead of multiplied. 5/8: only the first draw was considered.
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