Aptitude Questions: Probability Set 7

Hello Aspirants. Welcome to Online Maths in AffairsCloud.com. Here we are creating question sample in Probability, which is common for all the competitive exams. We have included Some questions that are repeatedly asked in exams !!

1. A box contain 4 white, 3 blue and 2 black marbles. If 2 marbles are picked up at random. What is the probability that both of them are black ?
   A.20
   B.1/36
   C.1/22
   D.36
   E.None of these
   
   Answer & Explanation

   Answer – B.1/36
   Explanation :
   P = 2C2/9C2 = 1/36
   
   
   
2. An urn contains 6 maroon, 3 pink and 4 white balls. If three balls are drawn What is the probability that all are pink or white?
   A.11/328
   B.7/212
   C.5/286
   D.9/127
   E.None of these
   
   Answer & Explanation

   Answer – C.5/286
   Explanation :
   P =3C3/13C3 + 4C3/13C3
   = 1/286 + 4/286 = 5/26
   
   
   
3. From a pack of 52 cards 3 cards are drawn one by one without replacements.Find the probability that both of them are king ?
   A.132/1338
   B.32/2340
   C.1/5525
   D.4/2755
   E.None of these
   
   Answer & Explanation

   Answer – C.1/5525
   Explanation :
   4/52*3/51*2/50 = 24/132600 = 4/22100 = 1/5525
   
   
   
4. If two dice are thrown simultaneously, what is the probability that the sum of the numbers appeared is less than seven?
   A.5/12
   B.7/12
   C.6/17
   D.13/27
   E.None of these
   
   Answer & Explanation

   Answer – A.5/12
   Explanation :
   Sum of the numbers can be 1,2, 3, 4, 5, and 6.
   1+2=  3
   1+3 = 4
   1+4 = 5
   1+5 = 6
   2+3 = 5
   3+2 = 5
   2+4 = 6
   4+2 = 6……..etc
   n (E) = 15, n (S) = 36
   P (E) =15/36  = 5/12
   
   
   
5. A box contains 5 white, 4 green, 2 blue and 3 black marbles. If 2 marbles are drawn at random, what is the probability that both are green or at least one is green ?
   A.46/91
   B.32/97
   C.16/75
   D.1/54
   E.None of these
   
   Answer & Explanation

   Answer – A.46/91
   Explanation :
   4C2+(4C1*10C1)/12C2 = 6+40/91 = 46/91
   
   
   
6. In a shelf, there are 7 Banking awareness, 6 English and 5 GK books. One book is picked up randomly. What is the probability that it is neither in Banking awareness nor in GK ?
   A.1/13
   B.2/17
   C.1/3
   D.12/27
   E.None of these
   
   Answer & Explanation

   Answer – C.1/3
   Explanation :
   P = 6/18 = 1/3
   
   
   
7. A suitcase contains 4 blue shirts, 5 red shirts and 3 white shirts.If 4 shirts are drawn what is the probability that exactly one of them is blue ?
   A.113/218
   B.14/167
   C.123/234
   D.224/495
   E.None of these
   
   Answer & Explanation

   Answer – D.224/495
   Explanation :
   P = 4C1*8C3/12C4 = 4*56/495 = 224/495
   
   
   
8. A bag contains 4 white, 8 black and 6 blue balls. If two balls are drawn at random, find the probability of both the balls being black?
   A.22/137
   B.14/123
   C.28/253
   D.7/105
   E.None of these
   
   Answer & Explanation

   Answer – C.28/253
   Explanation :
   n(S) = 18C2 = 153
   There are eight black balls, out of which two balls are drawn in 8C2 ways.
   n(E) = 28
   P(E) = 28 /153 = 28/153
   
   
   
9. The ratio of the number of girls to the number of boys is the 5 : 2 in a class of 21 students. A group of three students is to to be selected at random amongst them. What is the probability that the selected group of students contain one boy and two girls?
   A.45/266
   B.32/343
   C.120/217
   D.46/267
   E.None of these
   
   Answer & Explanation

   Answer – A.45/266
   Explanation :
   5:2 = 15+6 = 21
   n(S) = 21C3 = 1330
   n(E) = 15C1 × 6C2 = 15 × 15 = 225
   P = 225/1330 = 45/266
   
   
   
10. A bag 5 red and 8 white balls.Two draws of three balls each are made.What is the probability that the balls were pink in the first draw and white in the second draw ?
    A.23/345
    B.140/20449
    C.20440/110
    D.230/23454
    E.None of these
    
    Answer & Explanation

    Answer – B.140/20449
    Explanation :
    5C3/13C3 *8C3/13C3 = 60/286*56/286 = 140/20449