New RBI Grade B 2025 Notification will come Soon! Enroll Here

    Question

    16 defective pens are accidentally mixed with 155

    good ones. It is not possible to just look at a pen and tell whether or not it is defective. One pen is taken out at random from this lot. Determine the probability that the pen is taken out is a good one.
    A 0.906 Correct Answer Incorrect Answer
    B 0.933 Correct Answer Incorrect Answer
    C 0.932 Correct Answer Incorrect Answer
    D 0.884 Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    Numbers of pens = Numbers of defective pens + Numbers of good pens
    ∴ Total number of pens = 155 + 16 = 171 pens
    P(E) = (Number of favourable outcomes) / (Total number of outcomes)
    P(picking a good pen) = 155/171 = 0.906

    Practice Next