An urn contains 3 red and 4 green marbles. If three marbles

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An urn contains 3 red and 4 green marbles. If three marbles are picked at random, what is the probability that two are green and one is red ?

1. 3/7
2. 18/35
3. 5/14
4. 4/21

Correct Option: B

Number of ways to select 3 marbles out of 7 marbles = n(s) = ⁷C₃ = 35
Probability that 2 are green and 1 is red = n(E) = ⁴C₂ x ³C₁ = 18
∴ Required probability = 18/35