Permutation and Combination (Algebra, Teaching Exam Part-2)

Total Questions: 50

21. Everybody in a room shakes hands with everybody else. The total number of handshakes is 66. The total number of persons in the room is- [SECTION B PGT TIER-I 31.11.2014]

Correct Answer: (b) 12
Solution:

22. The total number of 9 digit numbers which have all different digits is- [SECTION B PGT TIER-I 31.11.2014, TGT 2001]

Correct Answer: (c) 9×9!
Solution:

23. Solve the following equation? [SECTION B (TGT & PGT) TIER-I 31.11.2014]

Correct Answer: (a)
Solution:

24. In a leap year the probability of having 53 Sundays or 53 Mondays is- [SECTION B PGT TIER-I 31.11.2014]

Correct Answer: (b) 3/7
Solution:

25. The probability that in a family of 5 members, exactly two members have birthday on Sunday, is [SECTION B PGT TIER-I 31.11.2014]

Correct Answer: (d)
Solution:

26. If the events A and B are independent, then P(A∩B) is equal to - [SECTION B PGT TIER-I 31.11.2014]

Correct Answer: (c) P(A).P(B)
Solution:

If the events are independent then
P(A∩B) = P(A).P(В)

27. A bag contains 5 red and 3 blue balls. If 3 balls are drawn at random without replacement the probability of getting exactly one red ball is [SECTION B PGT TIER-I 31.11.2014]

Correct Answer: (c) 15/56
Solution:

28. There are 10 lamps in a hall. Each of them can be switched on independently. The number of ways in which the hall can be illuminated is- [JDD-75-PGT TIER II-X-15 28.06.2015]

Correct Answer: (c) 1023
Solution:

29. How many diagonals can be drawn in a polygon of n sides? [JDD-75-PGT TIER II-X-15 28.06.2015]

Correct Answer: (c)
Solution:

30. If the number of diagonals of a 'n' sided polygon is equal to twice of its sides, then the value of n is equal to – [JDD-75-PGT TIER II-X-15 28.06.2015]

Correct Answer: (a) 7
Solution: