. The number of ways in which a committee of 3 ladies and 4 gentlemen can
be appointed from a meeting consisting of 8 ladies and 7 gentlemen, if Mrs X refuses to serve in a committee if Mr. Y is a member is
A: 1960
B: 1540
C: 3240
D: none of these
Best Answer
Explanation:
3 ladies out of 8 can be selected in C38 ways and 4 gentlemen out of 7 in C47 ways.
Now each way of selecting 3 ladies is associated with each way of selecting 4 gentlemen.
So, the required number of ways = C38×C47= 56×35=1960.
We can now find the number of committees of 3 ladies and 4 gentlemen in which both Mrs X and Mr Y are members.
In this case we can select 2 other ladies from the remaining 7 in C27ways and 3 other gentlemen from the remaining 6 in C36ways.
Therefore the number of ways in which both Mrs X and Mr Y are always included C27×C38=21×20=420.
Hence the required number of committee in which Mrs X and Mr Y do not serve together =1960-420=1540.
Final answer:
The number of ways is 1540, (B) option is correct
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