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  • Question
  • There are 8 blue and 4 white balls in a bag . A ball is drawn at random. Without replacing it another ball is drawn. Find the probability that both the balls drawn are blue?


  • Options
  • A. 7/33
  • B. 14/33
  • C. 11/33
  • D. 2/33

  • Correct Answer
  • 14/33 

    Explanation

    Total number of balls in the bag = 12
    Probability of drawing one blue ball in the first draw P(E1) = 8C1 / 12C1
    = 8/12 = 2/3

    After the first drawn of a blue ball, now there are 7 blue and 4 white ball in the bag. Total number of the balls in the bag is 11.

    Probability of drawing one blue ball in the second drawn = P(E2) = 7C1 /11C1 = 7/11

    ? Probability that both are blue P(E1 ? E2) = P(E1) x P(E2)
    = 2/3 x 7/11 = 14 / 33


  • Probability problems


    Search Results


    • 1. 
      A bag contains 5 white, 7 red and 8 black balls. If 4 balls are drawn one by one with replacement, what is the probability that all are white?

    • Options
    • A. 1/256
    • B. 1/16
    • C. 4/20
    • D. 4/8
    • Discuss
    • 2. 
      A and B aim a target. The Probability that A hits the target is 5/7 and B hits the target in 7/10. What is the probability that exactly one of them hits the target?

    • Options
    • A. 21/10
    • B. 29/70
    • C. 31/70
    • D. 33/70
    • Discuss
    • 3. 
      What is the possibility of getting at least 6 heads, if eight coins are tossed simultaneously?

    • Options
    • A. 37/256
    • B. 25/57
    • C. 1/13
    • D. None of these
    • Discuss
    • 4. 
      Two unbiased dice are thrown simultaneously. the probability of getting the sum divisible by 3, is?

    • Options
    • A. 11/36
    • B. 12/36
    • C. 13/36
    • D. 17/36
    • Discuss
    • 5. 
      Cards are down at random from a pack of 200 cards numbered 1 to 200. Find the probability of drawing a number which is a perfect cube?

    • Options
    • A. 1/40
    • B. 3/40
    • C. 7/40
    • D. 19/40
    • Discuss
    • 6. 
      Two dice are thrown simultaneously. What is the probability of getting a number other than 4 on any dice?

    • Options
    • A. 25/36
    • B. 1/3
    • C. 17/36
    • D. 2/3
    • Discuss
    • 7. 
      Number 1 to 25 are marked on tokens of equals size one on each. A token is drawn at random. Find the probability of getting a number divisible by both 2 and 3?

    • Options
    • A. 4/25
    • B. 7/25
    • C. 2/25
    • D. 9/25
    • Discuss
    • 8. 
      A complete cycle of a traffic light takes 60 s. During each cycle the light is green for 25 s, yellow for 5 s and red for 30 s. At a randomly chosen time, the probability that the light will not be green is?

    • Options
    • A. 1/3
    • B. 1/4
    • C. 5/12
    • D. 7/12
    • Discuss
    • 9. 
      The probability that a man will live 10 more year is 1/4 and the probability that his wife will live 10 more year is 1/3. Then, the probability that none of them will be alive after 10 yr, is?

    • Options
    • A. 5/12
    • B. 1/2
    • C. 7/12
    • D. 11/12
    • Discuss
    • 10. 
      The letters B, G, I, N, R are rearranged to form the word 'BRING'. Find its probability?

    • Options
    • A. 1/120
    • B. 1/54
    • C. 1/24
    • D. 5/5 x 42
    • Discuss


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