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 5 of 10.
Shiva said:
8 years ago
I am confused in the second step, Please explain it.
Payal said:
10 years ago
Second step is not clear.
Harika said:
8 years ago
I'm bit confused that why here use multiplication? Please tell me.
Pranali said:
9 years ago
In first step (6c2 * 4c2).
Send step ( (6*5/2*1) * (4*3/2*1) ).
How?
I can't understand it
Send step ( (6*5/2*1) * (4*3/2*1) ).
How?
I can't understand it
Shivaraj said:
9 years ago
@Neema.
It's mentioned, read question clearly.
It's mentioned, read question clearly.
DANIEL said:
9 years ago
Why not 4 girls?
Pallavi said:
1 decade ago
Another easy method is
1-(4C4/10C4)
=1-(1/210)
=209/210
Therefore 209 times out of possible 210.
1-(4C4/10C4)
=1-(1/210)
=209/210
Therefore 209 times out of possible 210.
Anusha said:
1 decade ago
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).
Why to change only the first term and last term with formula. Why don't the formula apply to the other terms. Please Explain?
Required number of ways = (6C1 x 4C3) + (6C2 x 4C2) + (6C3 x 4C1) + (6C4)
= (6C1 x 4C1) + (6C2 x 4C2) + (6C3 x 4C1) + (6C2).
Why to change only the first term and last term with formula. Why don't the formula apply to the other terms. Please Explain?
Kashika shekhar said:
1 decade ago
I am not able to apply different types of logic in different questions. Please tell me some logic for appying the formulas.
Shanmuga kumar said:
1 decade ago
How do you get 4 members in group? please explain.
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