• # 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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