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  • Question
  • A coin is tossed twice if the coin shows head it is tossed again but if it shows a tail then a die is tossed. If 8 possible outcomes are equally likely. Find the probability that the die shows a number greater than 4, if it is known that the first throw of the coin results in a tail


  • Options
  • A. 1/3
  • B. 2/3
  • C. 2/5
  • D. 4/15

  • Correct Answer
  • 1/3 

    Explanation

    Here Sample space S = { HH, HT, T1, T2, T3, T4, T5, T6 }

     

    Let A be the event that the die shows a number greater than 4 and B be the event that the first throw of the coin results in a tail then,

     

     A = { T5, T6 }

     

     B = { T1, T2, T3, T4, T5, T6 }

     

    Therefore, Required probability =  P A B = P A ? B P B = 2 8 6 8 = 1 3


  • Probability problems


    Search Results


    • 1. If the difference between the mode and median is 2, then the difference between the median and mean is:

    • Options
    • A. 2
    • B. 1
    • C. 3
    • D. 4
    • Discuss
    • 2. A bag contains 5 red smileys, 6 yellow smileys and 3 green smileys. If two smileys are picked at random, what is the probability that both are red or both are green in colour?

    • Options
    • A. 7
    • B. 1/7
    • C. 3/7
    • D. 0
    • Discuss
    • 3. Out of 17 applicants 8 boys and 9 girls. Two persons are to be selected for the job. Find the probability that at least one of the selected persons will be a girl.

    • Options
    • A. 19/34
    • B. 5/4
    • C. 20/34
    • D. 25/34
    • Discuss
    • 4. If a box contains 10 bulbs,of which just three are defective. If a random sample of five bulbs is drawn, find the probability that the sample contains no defective bulbs.

    • Options
    • A. 5/12
    • B. 7/12
    • C. 3/14
    • D. 1/12
    • Discuss
    • 5. Ajay and his wife Reshmi appear in an interview for two vaccancies in the same post. The Probability of Ajay's selection is 1/7 and that of his wife Reshmi's selection is 1/5. What is the probability that only one of them will be selected?

    • Options
    • A. 5/7
    • B. 1/5
    • C. 2/7
    • D. 2/35
    • Discuss
    • 6. A room contains 3 brown, 5 black and 4 white chairs. Two chairs are picked and are put in the lawn. What is the probability that none of the chairs picked is white ?

    • Options
    • A. 14/33
    • B. 14/55
    • C. 12/55
    • D. 13/33
    • Discuss
    • 7. From a pack of 52 cards, 3 cards are drawn. What is the probability that one is ace, one is queen and one is jack?

    • Options
    • A. 19/5525
    • B. 16/5525
    • C. 17/5525
    • D. 7/5525
    • Discuss
    • 8. fifteen persons are sitting around a circular table facing the centre. What is the probability that three particular persons sit together ?

    • Options
    • A. 3/91
    • B. 2/73
    • C. 1/91
    • D. 3/73
    • Discuss
    • 9. The first 8 alphabets are written down at random. what is the probability that the letters b,c,d,e always come together ?

    • Options
    • A. 1/7
    • B. 8!
    • C. 7!
    • D. 1/14
    • Discuss
    • 10. In a box, there are 9 blue, 6 white and some black stones. A stone is randomly selected and the probability that the stone is black is ¼. Find the total number of stones in the box?

    • Options
    • A. 15
    • B. 18
    • C. 20
    • D. 24
    • Discuss


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