Probability (Railway Maths)

Total Questions: 29

11. Two integers are selected at random from the first 11 natural numbers. If the sum of the integers is even, then the probability that both the numbers are odd is: [RRB NTPC 01/03/2021 (Morning)]

Correct Answer: (b) 3/5
Solution:

12. Five salesmen A, B, C, D and E of a company are considered for a three member trade delegation to represent the company at an international trade conference. What is the probability that A gets selected? [RRB NTPC 01/03/2021 (Morning)]

Correct Answer: (a) 3/5
Solution:

13. A card is drawn at random from a pack of playing cards. What is the probability of getting a face card? [RRB NTPC 04/03/2021 (Morning)]

Correct Answer: (d) 3/13
Solution:

14. In tossing three coins at a time, the probability of getting at least one head is: [RRB NTPC 04/03/2021 (Morning)]

Correct Answer: (a) 7/8
Solution:

15. A dice is thrown twice and the sum of the appearing numbers is 10. Then the probability that the number 5 has appeared at least once is: [RRB NTPC 07/03/2021 (Evening)]

Correct Answer: (b) 1/3
Solution:

16. For two events A and B, P(A) = 1/3, P(B) = 1/4 and P(A ∪ B) = 1/2 find P(A/B) = ? [RRB NTPC 08/03/2021 (Evening)]

Correct Answer: (d) 1/3
Solution:

17. Two cards are drawn from a pack of 52 cards. The probability that out of 2 cards, one card is red and one card is black is: [RRB NTPC 08/03/2021 (Evening) ]

Correct Answer: (d) 26/51
Solution:

18. If different combinations are formed using the letters B,A,R,E and arranged in the order in which they would appear in an English dictionary, the combination ‘BARE’ will be at the __________ position. [RRB NTPC 11/03/2021 (Morning) ]

Correct Answer: (a) 8th
Solution:

19. 10 points are placed uniformly along the perimeter of a circle. Let A and B be two points among these such that they are the end points of a diameter. If a triangle formed using three of these points is chosen at random, what is the probability that it will lie completely on one side of AB, the points A and B being included? [RRB NTPC 11/03/2021 (Evening)]

Correct Answer: (c) 1/3
Solution:

20. If we select 3 persons randomly from a group, consisting of 4 men, 3 women and 2 boys, then the probability that 2 men are selected is: [RRB NTPC 13/03/2021 (Morning)]

Correct Answer: (a) 5/14
Solution: