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Aptitude - Permutation and Combination - Discussion

Discussion Forum : Permutation and Combination - General Questions (Q.No. 11)
Permutation and Combination
11.
In how many ways can a group of 5 men and 2 women be made out of a total of 7 men and 3 women?
63
90
126
45
135
Answer: Option
Explanation:

Required number of ways = (7C5 x 3C2) = (7C2 x 3C1) = 7 x 6 x 3 = 63.
2 x 1

Discussion:
51 comments Page 4 of 6.
Aswin said:   1 decade ago
Another question : how to select 6 people from a group of 10 so that two of them does not come together?
Chandan said:   1 decade ago
Why multiplication not addition?
Pooja said:   1 decade ago
I understood that thanks! we have to use nCr=nCn-r.
Vinod Rathod said:   1 decade ago
Lets do by this way :

As you said that (7c5*3c2) = (7c2*3c1).

7/5*3/2 = 7/2*3/1 = 63.
Niyati Bafna said:   1 decade ago
Are there any more problems, perhaps of a slightly advanced kind, on the net? If so, on which sites can they be found?
Moni said:   1 decade ago
For ex. Take 7C5, 5 is more than a half of 7. So we can use the formula nC (n-r) when are is more than half of n.

Similarly 3C2 is made as 3C1. I hope you have understood.
Srikanth said:   1 decade ago
@teja. As this a problem f selection you use combination. It means calculating 7c5 is a bit more tedious when compared to calculating 7c2.
Teja said:   1 decade ago
Hey see you said that 7c5*3c2 is long procedure. That the thing we take ncr formula. ?and second thing why we take that formula in this problem? am not?
Nirmal said:   1 decade ago
(7C2 x 3C1) = 7 x 6 x 3

How it happened explain please?
Ankur anand said:   1 decade ago
Why combination why not permutation ?

Similar as that of the arranging of letters the people are diffrent so there can be many ways by permutation.
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