mathematics puzzle

@banashree-patra-m0OJwR • Oct 25, 2024

Oct 25, 2024

1.4K

mathematics

A family I know has several children. Each boy in this family has as many sisters as brothers but each girl has twice as many brothers as sisters. How many brothers and sisters are there?

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Banashree Patra

@banashree-patra-m0OJwR • Aug 18, 2011

A family I know has several children. Each boy in this family has as many sisters as brothers but each girl has twice as many brothers as sisters. How many brothers and sisters are there?A family I know has several children. Each boy in this family has as many sisters as brothers but each girl has twice as many brothers as sisters. How many brothers and sisters are there.
...........plz answer this question
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Kaustubh Katdare

@thebigk • Aug 18, 2011

Thread moved to quiz/puzzles/mathematics section with a better title.
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RajdeepCE

@rajdeepce-7UdrG8 • Aug 18, 2011

There are multiple soultion to this puzzle, the smalles solution is 2 brother & 2 sister. The series can be developed as following,

No of Brother : 2,4,6,8,10,...
No of Sister : 2,3,4,5,6,...

It is easy to derive the expression for the same based on this.
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vinci

@vinci-e4PtMU • Sep 3, 2011

3 sisters and 4 brothers .So easy,

Give me more puzzles
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Banashree Patra

@banashree-patra-m0OJwR • Sep 3, 2011

thanks guysssssssssssssssssssssssssss................
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vinci

@vinci-e4PtMU • Sep 3, 2011

2 brother and 2 sister cant be the solution to this problem
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simplycoder

@simplycoder-NsBEdD • Sep 3, 2011

I dont think it has multiple answers as well(Inconsistent).
The system is very much consistent (has a unique answer).
4-boys, 3 girls.
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Sagar07

@sagar07-LecI1i • Sep 6, 2011

ya, even i thnk unique solution... 3 girls and 4 boys............
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RajdeepCE

@rajdeepce-7UdrG8 • Sep 6, 2011

I think you guys should think more before coming to a solution. Sorry no personal offense to any of you guys, I know you are all genius on your own.

Let me expain you in simple words,
1) First Case, 2 brother & 2 sister
==> each girl has 1 sister & 2 brother so condtion is met for the puzzle.
2) Second case, 4 brother & 3 sister
==> each girl has 2 sister & 4 brother, so condition is true here too... :O
3) Third case, 6 brother & 4 sister
==> each girl has 3 sister & 6 brother, so maybe this is true too, I guess.

So basically when you counting than you should not count the girl itself in number of sisters.
And now let we have a equation for the puzzle,

# of Boys = 2x
# of Girls = x + 1
where x = 1,2,3,4,5,6,...,n
By the way even we can get the solution for x=0, cause 1 girl has no sister(0) and 0 x 2 = 0 brother too.

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Sagar07

@sagar07-LecI1i • Sep 7, 2011

@ rajdeep: there are 2 conditions given in a question.... u r considering only 1.... each boy in a family has as many brothers as sisters... so, only 4 boys and 3 girls is a solution...
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RajdeepCE

@rajdeepce-7UdrG8 • Sep 8, 2011

Thanx Sagar for pointing out that point. It went totally unnoticed by me. Sorry for that.
By the way still it has more than one solution, which can satisfy the condition.
Here it is,
1 = > Only 1 Brother
2 = > Only 1 Sister
3 => As we all said, 3 Sister & 4 Brother.
😀
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simplycoder

@simplycoder-NsBEdD • Sep 8, 2011

RajdeepCE :
I dont think you can solve equations by multiplying by 0 on both sides, well we are aware that its not correct, Its a fundamental rule, all operators must satisfy their inverses.
If a is added to b to get c, then a subtracted from c should yeild b.
If a is multiplied by b to get c, then c divided by a should yeild b. Does your multiplication holds this rule valid?

Physically, there is nothing as 0 or infinity. Mathematicians chose 0 as the smallest number one could think of and infinity as largest number.
Hence Limits were introduced. We cannot treat 0 and infinity physically.

Taking matrices would help you to understand this system is consistent.

Take care,
Ciao.
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