CLASS_11_MATHS_SOLUTIONS_NCERT

Class XI Chapter 7 – Permutation and Combination Maths
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48 cards in 48 C
4
ways.
Thus, by multiplication principle, required number of 5 card combinations
48 4 48! 4!
C4 C1
4!44! 1!3!
48 47 46
45
4!
4! 3 21
778320
Question 7:
In how many ways can one select a cricket team of eleven from 17 players in which only 5
players can bowl if each cricket team of 11 must include exactly 4 bowlers?
Solution 7:
Out of 17 players, 5 players are bowlers.
A cricket team of 11 players is to be selected in such a way that there are exactly 4 bowlers.
4 bowlers can be selected in 5 C
4
ways and the remaining 7 players can be selected out of the 12
players in
12
C 7
ways.
Thus, by multiplication principle, required number of ways of selecting cricket team
5 12 5! 12! 12111098
C4 C7
5! 3960
4!1! 7!5! 5! 43 21
Question 8:
A bag contains 5 black and 6 red balls. Determine the number of ways in which 2 black and 3
red balls can be selected.
Solution 8:
There are 5 black and 6 red balls in the bag.
2 black balls can be selected out of 5 black balls in 5 C
2
ways and 3 red balls can be selected out
of 6 red balls in 6 C
3
ways.
Thus, by multiplication principle, required number of ways of selecting 2 black and 3 red balls
5 6 5! 6! 5
4 65
4
C2 C3
10 20 200 .
2!3! 3!3! 2 321
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