Aptitude - Permutation and Combination - Discussion

Discussion Forum : Permutation and Combination - General Questions (Q.No. 6)
6.
In a group of 6 boys and 4 girls, four children are to be selected. In how many different ways can they be selected such that at least one boy should be there?
159
194
205
209
None of these
Answer: Option
Explanation:

We may have (1 boy and 3 girls) or (2 boys and 2 girls) or (3 boys and 1 girl) or (4 boys).

Required number
of ways
= (6C1 x 4C3) + (6C2 x 4C2) + (6C3 x 4C1) + (6C4)
= (6C1 x 4C1) + (6C2 x 4C2) + (6C3 x 4C1) + (6C2)
= (6 x 4) + 6 x 5 x 4 x 3 + 6 x 5 x 4 x 4 + 6 x 5
2 x 1 2 x 1 3 x 2 x 1 2 x 1
= (24 + 90 + 80 + 15)
= 209.

Discussion:
92 comments Page 8 of 10.

Hitesh said:   1 decade ago
What about when there was asked for at most 2 boys?

Shreu said:   1 decade ago
But the also there the children how it is possible?

Shanmuga kumar said:   1 decade ago
How do you get 4 members in group? please explain.

Shivaraj said:   9 years ago
@Neema.

It's mentioned, read question clearly.

Galla said:   1 decade ago
Wow your various explanations really did help.

Sugumar said:   10 years ago
Why didn't you take 4 girls out of 4 girls?

Dhanraj said:   6 years ago
Thanks for explaining it in detail @Shivam.

P.krishna reddy said:   5 years ago
Atleast one = Total - None = 10c4-1 = 209.
(4)

Abhishek said:   1 decade ago
Udaya its easy. But its more calculative.

Sathvika said:   6 years ago
4c2 = 4!/2!*(4-2)!.
= 4 * 3/2 * 2,
= 3.


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