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

    Question

    34 pens are there in a box where 10 are red pens,

    ‘p’ are blue pens and remaining are black pens. If a pen is picked, the probability of getting blue pen is 0.5. Find the ratio of the number of blue pens and black pens.
    A 5:2 Correct Answer Incorrect Answer
    B 3:4 Correct Answer Incorrect Answer
    C 17:7 Correct Answer Incorrect Answer
    D 7:1 Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    Probability of getting a blue  pen , => p/34 = 1/2 => p = 17 So, number of black  pens  = 34 – 10 – 17 = 7 Required ratio = 17 : 7 

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