Quantitative Aptitude: Probability Questions – Set 10

1. A bag contains 12 white and 18 black balls. Two balls are drawn in succession without replacement.
   37/145
   35/142
   33/141
   36/145
   31/140
   Option D
   Required probability,
   =(2/5)×(18/29)
   =36/145
   
   
    



2. There are four hotels in a town. If 3 men check into the hotels in a day then what is the probability that each checks into a different hotel?
   1/4
   2/5
   3/8
   4/9
   2/7
   Option C
   Required probability
   =24/4^3
   =3/8
   
   
    



3. A card is drawn from a pack of 52 cards. The card is drawn at random. What is the probability that it is neither a spade nor a Jack?
   8/11
   5/7
   4/5
   9/13
   8/13
   Option D
   Probability of getting spade or a jack
   =(13+3)/52
   =4/13
   So probability of getting neither spade nor a jack
   =1−4/13
   =9/13
   
   
    



4. A bag contains 5 red and 3 green balls. Another bag contains 4 red and 6 green balls. If one ball is drawn from each bag. Find the probability that one ball is red and one is green.
   17/42
   21/40
   19/44
   20/43
   19/41
   Option B
   Required probability = 3/8+3/20 = 21/40
   
    



5. Two brother X and Y appeared for an exam. The probability of selection of X is 1/7 and that of B is 2/9. Find the probability that both of them are selected.
   4/65
   2/63
   2/65
   3/62
   2/61
   Option B
   Probability =(1/7)*(2/9)
   =2/63
   
   
    



6. Two brothers appeared for an exam. The probability of each of them getting selected is 1/4 and 1/6 respectively. Find the probability that only one of the two are selected.
   1/7
   1/5
   1/4
   1/2
   1/3
   Option E
   Probability that only of the two are selected
   = [(1/4)*(5/6)]+[(3/4)*(1/6)]
   = [5/24]+[3/24]
   = 8/24
   = 1/3
   
   
    



7. A card is selected at random from a pack of cards. After replacing it, another draw is made. Find the probability that the first card is a spade and the second is a club.
   1/18
   1/16
   1/17
   1/13
   1/15
   Option B
   P(drawing a spade) = 13/52 = 1/4
   P(drawing a club) = 1/4
   Probability = (1/4)*(1/4) = 1/16
   
   
    



8. A bag contains 2 red, 4 blue and 6 green balls. If one ball is drawn from the bag, what is the probability that it is red or green?
   2/3
   5/6
   5/9
   3/7
   2/5
   Option A
   Required Probability = 8/12 = 2/3
   
    



9. Two friends appear for an interview. The probability of each of them getting selected is 1/5 and 1/6 respectively. Find the probability that both are selected.
   1/35
   1/33
   1/30
   1/31
   1/29
   Option C
   P(both being selected)
   = (1/5)*(1/6)
   = 1/30
   
   
    



10. Three unbiased coins are tossed. What is the probability of getting at most two heads ?
    6/7
    3/5
    8/9
    7/8
    4/5
    Option D
    Probability = 7/8