Permutations and Combinations

A. 300
B. 450
C. 600
D. 750
Explanation:
The number of ways of selecting three men, two women and three children is:
= ⁴C₃ * ⁶C₂ * ⁵C₃
= (4 * 3 * 2)/(3 * 2 * 1) * (6 * 5)/(2 * 1) * (5 * 4 * 3)/(3 * 2 * 1)
= 4 * 15 * 10
= 600 ways.

A. 300
B. 600
C. 750
D. 900
Explanation:
Two men, three women and one child can be selected in ⁴C₂ * ⁶C₃ * ⁵C₁ ways
= (4 * 3)/(2 * 1) * (6 * 5 * 4)/(3 * 2) * 5
= 600 ways.

A. 720
B. 1440
C. 1860
D. 2160
In the word, “MATERIAL” there are three vowels A, I, E.
If all the vowels are together, the arrangement is MTRL’AAEI’.
Consider AAEI as one unit. The arrangement is as follows.
M T R L A A E I
The above 5 items can be arranged in 5! ways and AAEI can be arranged among themselves in 4!/2! ways.
Number of required ways of arranging the above letters = 5! * 4!/2!
= (120 * 24)/2 = 1440 ways.

A. 24
B. 23
C. 119
D. 120
Number of words which can be formed = 5! – 1 = 120 – 1 = 119.

A. 20
B. 54
C. 42
D. 60
Explanation:
There are three ladies and five gentlemen and a committee of 5 members to be formed.
Number of ways such that two ladies are always included in the committee = ⁶C₃ = (6 * 5 * 4)/6 = 20.

A. 4000
B. 2160
C. 4320
D. 5300
Explanation:
x Not younger_______ ↑
The last ball can be thrown by any of the remaining 6 players. The first 6 players can throw the ball in ⁶P₆ ways.
The required number of ways = 6(6!) = 4320

A. 4800
B. 5760
C. 2880
D. 15000
Explanation:
Treat all boys as one unit. Now there are four students and they can be arranged in 4! ways. Again five boys can be arranged among themselves in 5! ways.
Required number of arrangements = 4! * 5! = 24 * 120 = 2880.