10th Class Mathematics Probability Question Bank Probability

  • question_answer A box contains 19 balls bearing numbers 2, 3,...., 19. A ball is drawn at random from the box. What is the probability that the number on the ball is
    (i) A prime number ?
    (ii) Divisible by 3 or 5?
    (iii) Neither divisible by 5 nor by 10?
    (iv) An even number?
               

    A)

    (i) (ii) (iii) (iv)
    3/19 7/19 1/19 9/19
                   

    B)

    (i) (ii) (iii) (iv)
    1/19 1/19 8/19 9/19
                   

    C)

    (i) (ii) (iii) (iv)
    8/19 8/19 16/19 9/19
                   

    D)

    (i) (ii) (iii) (iv)
    8/19 8/19 17/19 9/19

    Correct Answer: C

    Solution :

    Total number of possible outcomes =19     (i) Prime numbers are 2, 3, 5, 7, 11, 13, 17, 19. \[\therefore \] Probability of numbers being prime = 8/19 (ii) Numbers divisible by 3 or 5 are 3, 5, 6, 9, 10, 12, 15,18.                              \[\therefore \] Required probability = 8/19                (iii) Numbers neither divisible by 5 nor by 10 are 1,2, 3,4, 6, 7, 8, 9, 11, 12, 13, 14, 16, 17, 18, 19. \[\therefore \] Required probability =16/19               (iv) Even numbers are 2, 4, 6, 8, 10, 12, 14, 16, 18. \[\therefore \] Required probability =9/19                               

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