Quantitative Aptitude: Probability Questions – Set 14

1. There are 5 boys and 3 girls. A group of 3 members is to be made. Find the probability that either there are 2 boys and 1 girl or 2 girls and 1 boy?
   45/56
   44/54
   49/64
   52/58
   None of these
   Option A
   2 boy and 1 girl, prob. = 5C2*3C1/8C3
   2 girl and 1 boy, prob. = 5C1*3C2/8C3
   Add both the cases.
   
    



2. A carton contains 8 black and 7 grey balls. 2 balls are drawn one by one without replacement. What is the probability that the balls are alternately of different colors?
   7/10
   8/15
   9/14
   10/15
   None of these
   Option B
   When 1st is black, probability = 8/15 * 7/14
   When 1st is grey, probability = 7/15 * 8/14
   Add both cases.
   
    



3. A carton contains 10 electric lights from which 2 lights are defective. Two lights are chosen at random. What is the probability that one of them is defective?
   11/43
   14/45
   16/45
   15/35
   None of these
   Option C
   Probability=2C1*8C1/10C2
   
    



4. A bag contains 8 black and 7 grey balls. A ball is drawn out of it and put back in the bag. Then a ball is drawn again. What is the probability that both the balls are grey?
   49/225
   48/125
   25/95
   55/235
   None of these
   Option A
   
   
    



5. A bag contains 8 black and 7 grey balls. 2 balls are drawn one by one without replacement. What is the probability that the balls are alternately of different colors?
   3/14
   10/12
   8/15
   7/15
   6/15
   Option C
   When 1st is black, probability= 8/15 * 7/14
   When 1st is grey, probability = 7/15 * 8/14
   Add both cases.
   
    



6. A bag 5 ruby and 8 white balls.Two draws of three balls each are made.What is the probability that the balls were ruby in the first draw and white in the second draw ?
   140/20449
   145/20445
   20550/150
   Cannot be determined
   None of these
   Option A
   5C3/13C3 *8C3/13C3
   
    



7. The ratio of the number of womens to the number of mens is 5 : 2 in a class of 21 persons. A group of three students is to to be selected at random amongst them. What is the probability that the selected group of persons contain one mens and two womens?
   51/260
   45/266
   40/55
   37/255
   None of these
   Option B
   n(S) =21C3 = 1330
   n(E) =15C1 × 6C2 = 15 × 15 = 225
   Probability = 225/1330 = 45/266
   
    



8. A bag contains 4 weige, 8 beige and 6 blue balls. If two balls are drawn at random, find the probability of both the balls being beige?
   15/154
   25/152
   28/253
   27/250
   None of these
   Option C
   n(S) =18C2 =153
   n(E) = 28
   P(E) = 28 /153 = 28/153
   
    



9. In a shelf, there are 7 Computer, 6 Maths and 5 CA books. One book is picked up randomly. What is the probability that it is neither in Computer nor in CA ?
   1/5
   1/8
   1/3
   1/7
   None of these
   Option C
   Probability=6/18
   
    



10. If two dices are thrown simultaneously, what is probability that sum of numbers appeared is less than 7?
    5/12
    7/12
    9/14
    10/15
    None of these
    Option A