siblings
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3 people have exactly 2 siblings. This means three of them are siblings.
4 people have exactly one sibling.
Total no of ways of selecting 2 people from 7 = 7C2 = 21
No of ways favorable ways.
1. If we select One from the group of 3(2 siblings) and one from the group of 4(1 sibling) = 3C1*4C1 = 12
2. If we select 2 from the group of 4 who are not siblings = 4C2( Total Selections) - 2 ( Selections with siblings) = 4
Probability = 16/21.
Thanks
raama
4 people have exactly one sibling.
Total no of ways of selecting 2 people from 7 = 7C2 = 21
No of ways favorable ways.
1. If we select One from the group of 3(2 siblings) and one from the group of 4(1 sibling) = 3C1*4C1 = 12
2. If we select 2 from the group of 4 who are not siblings = 4C2( Total Selections) - 2 ( Selections with siblings) = 4
Probability = 16/21.
Thanks
raama
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Four of them has exactly one siblingFeruza Matyakubova wrote:thanks!
but i still can't understand the second step in solving a problem. can you please elaborate on that part?
a,b,c,d are the members of the group.
Assume that a,b and c,d are siblings.
2 people from 4 will be selected in 4C2 = 6 ways.
These 6 ways include selecting (a,b) and (c,d). We have to exclude them.
So 6 -2 = 4 ways we can select 2 people who are not sibllings.
Thanks
Raama
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No of ways favorable ways.
1. If we select One from the group of 3(2 siblings) and one from the group of 4(1 sibling) = 3C1*4C1 = 12
2. If we select 2 from the group of 4 who are not siblings = 4C2( Total Selections) - 2 ( Selections with siblings) = 4
Question: In this why are we not considering 2 from group of 3 men who are not siblings??
1. If we select One from the group of 3(2 siblings) and one from the group of 4(1 sibling) = 3C1*4C1 = 12
2. If we select 2 from the group of 4 who are not siblings = 4C2( Total Selections) - 2 ( Selections with siblings) = 4
Question: In this why are we not considering 2 from group of 3 men who are not siblings??
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Each one from that group has 2 siblings.Tryingmybest wrote:No of ways favorable ways.
1. If we select One from the group of 3(2 siblings) and one from the group of 4(1 sibling) = 3C1*4C1 = 12
2. If we select 2 from the group of 4 who are not siblings = 4C2( Total Selections) - 2 ( Selections with siblings) = 4
Question: In this why are we not considering 2 from group of 3 men who are not siblings??
Like A has B and C as siblings.
B has A and C as siblings.
C has A and B as siblings.
Thanks
Raama
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Here is my Vision of it
A-B C- D X- Y-Z
- denotes siblings
Selecting 2 from 7 = 7 C2 = 21
Pairs which are not siblings = AC ,AD,AX,AY,AZ,BC,BD,BX,BY,BZ,CX,CY,CZ,DX,DY,DZ
So Probability = 16/21
Thanks
A-B C- D X- Y-Z
- denotes siblings
Selecting 2 from 7 = 7 C2 = 21
Pairs which are not siblings = AC ,AD,AX,AY,AZ,BC,BD,BX,BY,BZ,CX,CY,CZ,DX,DY,DZ
So Probability = 16/21
Thanks