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Aptitude - Permutation and Combination - Discussion

Discussion Forum : Permutation and Combination - General Questions (Q.No. 1)
Permutation and Combination
1.
From a group of 7 men and 6 women, five persons are to be selected to form a committee so that at least 3 men are there on the committee. In how many ways can it be done?
564
645
735
756
None of these
Answer: Option
Explanation:

We may have (3 men and 2 women) or (4 men and 1 woman) or (5 men only).

Required number of ways = (7C3 x 6C2) + (7C4 x 6C1) + (7C5)
= 7 x 6 x 5 x 6 x 5 + (7C3 x 6C1) + (7C2)
3 x 2 x 1 2 x 1
= 525 + 7 x 6 x 5 x 6 + 7 x 6
3 x 2 x 1 2 x 1
= (525 + 210 + 21)
= 756.

Discussion:
137 comments Page 9 of 14.
Rampal said:   1 decade ago
Ya because they said to select at least 3 men which means we can select till 5.
Deus Simon said:   1 decade ago
The questions influencable but you did not talk about the of an event to occur.
Siva said:   1 decade ago
7c4 = 7c(7-3)

So came 7c3 @kranthi...

Based on the formula nCr = nC(n-r).
Sweety said:   1 decade ago
This method is ok but it will take much time to do in examination hall.
Ales said:   1 decade ago
Please can you tell me why we use combination instead of permutation?
Nivetha said:   6 years ago
Shouldn't we have to divide the whole answer by 13c5? Please tell me.
Bhargav said:   1 decade ago
Not a good answer to give please another method please easy method.
Venki said:   1 decade ago
Guys do you have any idea when to use permutations or combinations?
Naji said:   1 decade ago
How can we notice that we just have to select without arrangement ?
Anu said:   3 years ago
I haven't understood that point. Anyone, please help me to get it.
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