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

    Question

    A bag contains 30 white and some black balls. If the

    probability of drawing a black ball from the bag is 1.4 times that of drawing a white ball, find the number of black balls in the bag.
    A 32 Correct Answer Incorrect Answer
    B 45 Correct Answer Incorrect Answer
    C 42 Correct Answer Incorrect Answer
    D 54 Correct Answer Incorrect Answer

    Solution

      Given, Number of white balls = 30 Let x be the number of black balls. Total number of balls in the bag = 30 + x Also, the probability of drawing a black ball from the bag is 1.4 times that of drawing a white ball. ⇒ x/ (30 + x) = 1.4[30/ (30 + x)] =5x = 7×30 ⇒ x = 42 Hence, the number of black balls in the bag = 42.

    Practice Next

    Relevant for Exams: