The total number of possible proper three-digit integers that can be formed using 0,1,3,4 and 5 without repetition such that they are divisible by 5 are :
Answer: B Numbers divisible by 5 will end with either '0' or '5'. Total numbers ending with '0' = 4*3*1 = 12 Total of numbers ending with '5' = 3*3*1 = 9 Total such numbers = 21.
On the shelf there are 3 books on Psychology, 3 books on Management and 4 books on Economics.
Q. No. 1:
In how many ways can the books be arranged, if the books on only Management are to be arranged together ?
Answer: D Suppose total management book be 1 unit, then there are 8 books, which are arrange in 8! ways. Also, 3 management books are arranged in 3! ways. Total number of ways = 3!*8! = 241920.
Q. No. 2:
In how many ways can all the books be arranged at random ?
Answer: B In a mixed double of tennis game there is a pair of man and woman on each ride. So, total 2 men and 2 women are in each game. There are 9 men and 9 women. Ways to select 2 men = 9C2 Wives of these 2 men cannot play in same game. So ways to select 2 women = 7C2 In a game these 4 persons can be paired by 2 types. Total number of ways = 9C2*7C2*2 = 1512.