# Aptitude Questions: Probability Set 12

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Hello Aspirants.

Welcome to Online Quantitative Aptitude Section in AffairsCloud.com. Here we are creating question sample in Probability, which is common for all competitive exams. We have included Some questions that are repeatedly asked in bank exams !!

Bank PO Level Questions :-

1. A box contains 27 marbles some are blue and others are green. If a marble is drawn at random from the box, the probability that it is blue is 1/3. Then how many number of green marbles in the box?
A. 10
B. 15
C. 14
D. 18
Answer – D. 18
Explanation :
Blue marble – x
xc1/27c1 = 1/3
x/27=1/3 —> x=27/3=9
No of green marbles = Total – Blue marble =27-9=18

2. In a bag there are 4 white, 4 red and 2 green balls. Two balls are drawn at random.What is the probability that at least one ball is of red colour?
A. 4/3
B. 7/3
C. 1/3
D. 2/3
Answer – D. 2/3
Explanation :
Total Balls =10
Other than red ball = 6c2
6c2/10c2=1/3 —> 1-1/3 = 2/3

3. Sahil has two bags (A & B) that contain green and blue balls.In the Bag ‘A’ there are 6 green and 8 blue balls and in the Bag ‘B’ there are 6 green and 6 blue balls. One ball is drawn out from any of these two bags. What is the probability that the ball drawn is blue?
A. 15/28
B. 13/28
C. 17/28
D. 23/28
Answer – A. 15/28
Explanation :
Total balls in A bag = 14, Total balls in A bag = 12
A bag = 1/2(8c1/14c1) = 2/7
B bag = 1/2(6c1/12c1) = 1/4 —> total Probability = 2/7 + 1/4 =15/28

4. In an examination, there are three sections namely Reasoning, Maths and English. Reasoning part contains 4 questions. There are 5 questions in maths section and 6 questions in English section. If three questions are selected randomly from the list of questions then what is the probability that all of them are from maths?
A. 7/91
B. 8/91
C. 2/91
D. 4/91
Answer – C. 2/91
Explanation :
Total no of questions= 15
Probability = 5c3/15c3 = 2/91

5. A basket contains 5 red 4 blue 3 green marbles. If three marbles picked up random, What is the probability that either all are green or all are red?
A. 1/20
B. 7/20
C. 3/20
D. 9/20
Answer – A. 1/20
Explanation :
Total Marbles = 12
Either all are green or all are red = 5c3 + 3c3
probability = 5c3 + 3c3/12c3 = 11/220 = 1/20

6. A basket contains 5 red 4 blue 3 green marbles. If three marbles picked up random, What is the probability that at least one is blue?
A. 41/55
B. 53/55
C. 47/55
D. 49/55
Answer – A. 41/55
Explanation :
Total Marbles = 12
other than blue 8c3 / 12c3 = 14/55
probability = 1-14/55 = 41/55

7. A basket contains 5 red 4 blue 3 green marbles. If two marbles picked up random, What is the probability that both are red?
A. 4/33
B. 5/33
C. 7/33
D. 8/33
Answer – B. 5/33
Explanation :
Total Marbles = 12
Probability = 5c2 / 12c2 = 5/33

8. A bag contains 5 red caps, 4 blue caps, 3 yellow caps and 2 green caps.If three caps are picked at random, what is the probability that two are red and one is green?
A. 22/55
B. 15/81
C. 10/91
D. 5/91
Answer – D. 5/91
Explanation :
Total caps = 14
Probability = 5c2 * 2c1/ 14c3 = 5/91

9. A bag contains 5 red caps, 4 blue caps, 3 yellow caps and 2 green caps. If four caps are picked at random, what is the probability that two are red, one is blue and one is green?
A. 22/1001
B. 80/1001
C. 21/1001
D. 55/1001
Answer – B. 80/1001
Explanation :
Total caps = 14
Probability = 5c2 * 4c1 * 2c1 / 14c4 = 80/1001

10. A bag contains 2 red caps, 4 blue caps, 3 yellow caps and 5 green caps. If three caps are picked at random, what is the probability that none is green?
A. 2/13
B. 3/13
C. 1/13
D. 5/13
Answer – B. 3/13
Explanation :
Total caps = 14
Probability = 5c0 * 9c3/ 14c3 = 3/13

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