A bag contains 4 red, 5 blue, and 6 green marbles. Two marbles are drawn sequentially without replacement. What is the probability that both marbles are red?
Answer and explanation
Correct answer: B.
- Step 1: Total marbles: .
- Step 2: Probability of first marble being red: .
- Step 3: Since drawn without replacement, remaining marbles are 14 with 3 red: .
- Step 4: Combined probability: .
Answer
\frac{2}{35}.
Why not the others: '' is the probability of drawing one red marble; '' assumes drawing with replacement; '' is an arithmetic error.
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