PLEASE HELP!

[Denis]

Hi Guys,

Soon I would have to take a very important math test.
Most questions will based on solving number series questions,
like (0, 1, 1, 3, 6, 9, 27, 31 ... what is next number? BTW What IS the next
number?) and logical questions like (Suzie has equal number of
brothers and sisters and Peter has twice as much sisters as brothers,
how many brothers are there in the family? I guess the answer would
be to create a three formulas g+b = total, b = g - 1 and 2g = b - 1,
then using the other two equasions find what total equal to and use
it to find brothers, right?) I know these are probably very simple
questions but I am really rusty on math.

Denis

 

[Beau]

The answer to 0, 1, 1, 3, 6, 9, 27, 31 ... is 124.

 

[BeefJurky]

well, the number sequence is +1, x1, +2, x2, +3, x3, +4.... etc.

0
1=0+1
1=1x1
3=1+2
6=3x2
etc.

yay

 

[dakata24]

wow, you guys are soo smart...


beau6183 and beefjurky for elite status!

 

[Kev]

did you just make up the sisters/brothers one out of thin air because it doesn't look like its possible to fit those requirements.

 

[Beau]

The formula you have is close, but not quite:

This is what I got

First, since Suzie cannot be her own sister, and Peter cannot be his own brother, you have to take the total of each sex, then subtract 1 respectively.
g = girls
b = boys

g+b=x
Suzie has equal brother and sisters, therefore, including Suzie there is one more girl than boys thus:
b = g + 1
Peter has twice as many sisters as brothers thus including Peter, there are 1 less than twice as many girls than boys:
g = 2(b - 1)

put them together to solve for b

b = 2(b-1) + 1

 

[Kev]

<< The formula you have is close, but not quite:

This is what I got

g+b=x
Suzie has equal brother and sisters, therefore, including Suzie there is one more girl than boys thus:
b = g + 1
Peter has twice as many sisters as brothers thus including Peter, there are 1 less than twice as many girls than boys:
g = 2(b - 1)

put them together to solve for b

b = 2(b-1) + 1 >>



That means there's 1 brother besides Peter, which doesn't work. Because if Pete has 1 bro, that means there are only 2 sisters in the family. If there are 2 sisters and Suzie is one of them, then Suzie has 1 sister and 2 bros which does not fit the first requirement of the problem (that she has equal bros and sisters). I hope I'm making some sense...

 

[Beau]

<<

<< The formula you have is close, but not quite: This is what I got g+b=x Suzie has equal brother and sisters, therefore, including Suzie there is one more girl than boys thus: b = g + 1 Peter has twice as many sisters as brothers thus including Peter, there are 1 less than twice as many girls than boys: g = 2(b - 1) put them together to solve for b b = 2(b-1) + 1 >>

That means there's 1 brother besides Peter, which doesn't work. Because if Pete has 1 bro, that means there are only 2 sisters in the family. If there are 2 sisters and Suzie is one of them, then Suzie has 1 sister and 2 bros which does not fit the first requirement of the problem (that she has equal bros and sisters). I hope I'm making some sense... >>



yeah, that's what I cam up with. The math is right, but the numbers are wrong in the story.

 

[Denis]

No, I didn't make these problems up but I could messed up in describing them

 

[Denis]

BTW How do you work out these problems? Is there some sort of a pattern or every case just has it's
own logic? Can you guys describe do find the answer?

 

[Kev]

I just tend to work it out in my head....I generally don't ask my brain how or why it works, I just go with the flow.

For this bro/sis one though, I wrote equations similar to the ones above but nothing worked. So I give up and now I'm going home. I really wish I could have done something productive today. Oh well.

 

[Beau]

<< BTW How do you work out these problems? Is there some sort of a pattern or every case just has it's own logic? Can you guys describe do find the answer? >>



I find that it is easier to work with just one variable. Each instance in solving, they'll give you how one variable compares to the other. Read the post above where I broke the story apart. I explained what each step did with the equation. Also, take the story problems literally.

 

[Haircut]

For the brothers and sisters one I get:

g=b+1

2(b-1)=g


Solve for b gives b=3 amd therefore g=4.

Discounting Suzie, there are 3 boys, 3 girls - equal numbers of each which is what we want.
Discounting Peter, there are 2 boys, 4 girls - twice the number of girls which is what we want.

 

[azazyel]

<< I generally don't ask my brain how or why it works, I just go with the flow >>

One of the best quotes I have seen here!!!

 

[NelsonMuntz]

<< The formula you have is close, but not quite:

This is what I got

First, since Suzie cannot be her own sister, and Peter cannot be his own brother, you have to take the total of each sex, then subtract 1 respectively.
g = girls
b = boys

g+b=x
Suzie has equal brother and sisters, therefore, including Suzie there is one more girl than boys thus:
b = g + 1
Peter has twice as many sisters as brothers thus including Peter, there are 1 less than twice as many girls than boys:
g = 2(b - 1)

put them together to solve for b

b = 2(b-1) + 1 >>


This isn't quite right either as has already been stated.
I had to look at it like:
b=g-1 - the number of boys without Suzie equals the number of girls, so you have to take suzie out to make an equality.
2(b-1)=g - after subracting peter out you need twice as many boys to equal the number of girls.
So, this means that the original post was right on one and you were right on the other.
I think somebody already said b=3 and g=4. With word problems it is very important to make sure the original creation of your formulas is correct.

 

[Beau]

<< I had to look at it like: b=g-1 - the number of boys without Suzie equals the number of girls >>


Ummm... don't you mean that the number of girls without Suzie equals the number of boys : G[total girls] - 1[suzie who is a girl] = B[total number of boys]



<< 2(b-1)=g - after subracting peter out you need twice as many boys to equal the number of girls. >>



You got it here.

 

[Denis]

bump

 

[Denis]

Guys how about links to online resources? Does anyone know any?