# Quantitative Aptitude: Probability Questions – Set 8

1. A basket contains 8 Blue and 10 Brown balls. There is another basket which contains 6 Blue and 8 Brown balls. One ball is to drawn from either of the two baskets. What is the probability of drawing a Blue ball?
55/126
55/63
37/126
46/63
None
Option A
Solution:
P(Blue ball from 1st basket)=1/2*8C1/18C1=4/18
P(Blue ball from 2nd basket)=1/2*6C1/14C1=3/14
P=4/18+3/14=55/126.
2. One card is drawn at random from a pack of 52 cards. What is the probability that the card drawn is either a black card or a queen?
7/9
4/9
11/13
7/13
None
Option D
Solution:
There are 26 black cards and 4 queen(2queen included in black cards)
P=(26C1+2C1)/52C1
28/52=7/13.
3. A bag contains 12 Green and 8 White balls. Four balls are drawn out one by one and not replaced. What is the probability that they are in alternate colours?
310/2425
308/4845
284/2425
273/4845
None
Option B
Solution:
P=12C1/20C1* 8C1/19C1*11C1/18C1*7C1/17C1
=12/20*8/19*11/18*7/17
=308/4845.
4. From a group of 4 men, 5 women and 3 children, 4 people are to be chosen to form a committee. What is the probability that the committee contains at least 1 each of men, women and children?
16/21
6/11
10/11
7/11
None
Option B
Solution:
No of ways 2M+1W+1C or 1M+2W+1C or 1M+1W+2C
P=(4C2*5C1*3C1 + 4C1*5C2*3C1+ 4C1*5C1*3C2)/12C4
=(90+120+60)/495
=270/495=6/11.
5. 8 persons are seated at a round table. What is the probability that 3 particular persons sit together?
2/9
4/9
1/7
2/7
None
Option C
Solution:
3 particular person always sit together, then total person =5+1=6
6 persons will sit in (6-1)!=5! At round table.
No of ways in which 3 persons always sit together=5!*3!
No of ways of sitting 8 persons at round table=(8-1)!=7!.
Then P= (5!*3!)/7! =1/7.
6. In a lottery, there are 12prizes and 25 blanks. A lottery is drawn at random. What is the probability of getting a prize?
12/37
1/9
15/37
2/7
None
Option A
Solution:
P=12C1/37C1
=12/37.

Question 7-8: In a bag , there are 5 Blue, 7 white and some Red balls. A ball is randomly selected and the probability that the ball is red is 2/5.

1. ind the total number of balls?
22
24
18
20
None
Option D
Solution:
Total probability=1
P(Red)=2/5
Then P(Blue and White)=1-2/5=3/5
3/5………. 12(5+7)
1 ……… ?==> 20balls.
2. If two balls are selected randomly, then what is the probability the selected balls are of same colour?
47/190
59/190
13/80
17/80
None
Option B
Solution:
P(balls are of same colour)=(5C2+7C2+8C2)/20C2
=(10+21+28)/190
=59/190.
3. A and B wrote an exam. The probability of A’s pass is 2/7 and the probability of B’s pass is 2/5. What is the probability that only one of them is passed out?
17/35
4/7
18/35
3/7
None
Option C
Solution:
A’= A’s fail and B’= B’s fail.
Therefore, p(A) = 2/7 and p(B) = 2/5,
P(A’) = 1 – P(A) = 1- 2/7 = 5/7 and P(B’) = 1- P(B) = 1- 1/5 = 4/5
Required probability= (2/7 * 4/5) + (2/5 * 5/7)
= (8/35 + 10/35) = 18/35.
4. In a school, 35% of the students play chess,45% play carom and 10% play both. If a student is selected at random, then the probability that he plays chess or carom is
1/10
2/5
7/10
3/10
None
Option C
Solution:
P(A or B)=P(A) + P(B)-P(A and B)
=35/100+45/100-10/100
=70/100=7/10.

## 5 Thoughts to “Quantitative Aptitude: Probability Questions – Set 8”

1. jaga

THANK U MAM

1. AmRITa @ bank po

Hiii from odisha??

1. jaga

yes..

2. AmRITa @ bank po

No9-p(b)=2/5(not 1/5)
No3-again starting from white

3. the walking dead

🙂