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?
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 numberof ways |
= (6C1 x 4C3) + (6C2 x 4C2) + (6C3 x 4C1) + (6C4) | |||||||||||||||||||
| = (6C1 x 4C1) + (6C2 x 4C2) + (6C3 x 4C1) + (6C2) | ||||||||||||||||||||
|
||||||||||||||||||||
| = (24 + 90 + 80 + 15) | ||||||||||||||||||||
| = 209. |
Discussion:
92 comments Page 7 of 10.
Kanchan said:
1 decade ago
4C4
How we get value by it? Means what it is? What is the meaning of it?
How we get value by it? Means what it is? What is the meaning of it?
Aarav said:
7 years ago
We can also apply nCr = n!/((r!)(n-r)!).
It's one of the formulae.
It's one of the formulae.
Anukul said:
1 decade ago
Hey Thiyanesh you are little bit confused, read the question again.
Thiyanesh said:
1 decade ago
In second step
Why we use the nCr formula only for 4C3 and 6C4?
Why we use the nCr formula only for 4C3 and 6C4?
Harika said:
8 years ago
I'm bit confused that why here use multiplication? Please tell me.
Amit said:
1 decade ago
It is very simple. Only read carefully after that ans we get.
Kayalvizhi said:
9 years ago
Can anyone explain how to derive this calculation? Please.
Rahul said:
10 years ago
Why we are not using nc(n-r) formula in all in 2nd step?
Shiva said:
8 years ago
I am confused in the second step, Please explain it.
Mujhse said:
10 years ago
What if the question was at least 2 boys? Need help.
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