IndiaBIX

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 13 of 14.
Leo said:   1 decade ago
--> (7C3 x 6C2) + (7C4 x 6C1) + (7C5)

Shouldn't it be like this? --> (7C3 x 6C2) x (7C4 x 6C1) x (7C5)
Siva said:   1 decade ago
7c4 = 7c(7-3)

So came 7c3 @kranthi...

Based on the formula nCr = nC(n-r).
Kranthi said:   1 decade ago
How 7C4 became 7C3 ?
Osei-tutu said:   1 decade ago
Please what is mean by 7C3. Please help.
Lana said:   1 decade ago
Hey can any one explain me how 210 came because I got 140 instead of 210.

Lookin forward for your support.
Kumamako said:   1 decade ago
I think that it should be 3*2^3*3-3
Renuka said:   1 decade ago
Because nCr = nCn-r.
Rajeev said:   1 decade ago
In the first step 7c5 converted 7c2 in the second step. But how ?
Bhargav said:   1 decade ago
How can you take a 3 men 2 women 4men and 1women and a 5 men please solve easy method.
Bhargav said:   1 decade ago
Not a good answer to give please another method please easy method.
Post your comments here:

Your comments will be displayed after verification.

Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers