New Enroll in RBI Grade B New Batch - Starts on May 21

    Question

    A basket contains 3 blue, 5black and 3 red pens.

    If 2 pens are drawn at random what is the probability

    that one is black and one is red ?
    A 2/33 Correct Answer Incorrect Answer
    B 1/11 Correct Answer Incorrect Answer
    C 3/11 Correct Answer Incorrect Answer
    D 8/33 Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    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

    Practice Next

    Relevant for Exams: