Question
If 2 pens are drawn at random what is the probability
that one is black and one is red ? A basket contains 3 blue, 5black and 3 red pens.Solution
Let S be the sample space. Then, N(S) = number of ways of drawing 2 pens out of 11 = ¹¹C₂ = (11 ×10 )/(2 ×1) = 55 Let E = event of getting the one black and one red pen out of 8 pen. n(E) = ⁵C₁ × ³C₁ = 5 × 3 = 15 n(P) = (n(E))/(n(S)) = 15/55 = 3/11

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