Permutations and Combinations 2 Question 8

8. A man X has 7 friends, 4 of them are ladies and 3 are men. His wife Y also has 7 friends, 3 of them are ladies and 4 are men. Assume X and Y have no common friends. Then, the total number of ways in which X and Y together can throw a party inviting

3 ladies and 3 men, so that 3 friends of each of X and Y are in this party, is

(2017 Main)

(a) 485

(b) 468

(c) 469

(d) 484

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Answer:

Correct Answer: 8. (a)

Solution:

  1. Given, X has 7 friends, 4 of them are ladies and 3 are men while Y has 7 friends, 3 of them are ladies and 4 are men.

Total number of required ways

=3C3×4C0×4C0×3C3+3C2×4C1×4C1×3C2+3C1×4C2×4C2×3C1+3C0×4C3×4C3×3C0=1+144+324+16=485



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