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The variable x is inversely proportional to the square of the variable

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The variable x is inversely proportional to the square of the variable [#permalink]

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New post 18 Sep 2015, 19:04
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The variable x is inversely proportional to the square of the variable y. If y is divided by 3a, then x is multiplied by which of the following?

a. 1/9a

b. 1/9a^2

c. 1/3a

d. 9a

e. 9a^2
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Re: The variable x is inversely proportional to the square of the variable [#permalink]

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New post 06 Nov 2015, 00:23
Tried this question

not sure how to set it up when the say inversely proportional

initially - did x= 1/y^2

But this yielded the wrong answer,

I then re examined the question and tried y^2/x =1

Which I then got y = SQR(X)

subbing into y/3a I got answer E)

not sure what is the correct way to do this. thanks!
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Re: The variable x is inversely proportional to the square of the variable [#permalink]

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New post 07 Nov 2015, 07:11
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Let , \(x = k *\frac{1}{y^2}\) , Where K is constant.

\(x = k * \frac{1}{(3a)^2}\) = \(k * \frac{1}{9a^2}\)

=> \(k = (9a^2)x\)

Ans E.
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Re: The variable x is inversely proportional to the square of the variable [#permalink]

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New post 13 Dec 2015, 09:32
GMATDemiGod wrote:
Tried this question

not sure how to set it up when the say inversely proportional

initially - did x= 1/y^2

But this yielded the wrong answer,

I then re examined the question and tried y^2/x =1

Which I then got y = SQR(X)

subbing into y/3a I got answer E)

not sure what is the correct way to do this. thanks!



hi, u missed a point, y is divided by 3a, i.e y^2 is divided by 9a^2.....
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Re: The variable x is inversely proportional to the square of the variable [#permalink]

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New post 13 Dec 2015, 09:32
GMATDemiGod wrote:
Tried this question

not sure how to set it up when the say inversely proportional

initially - did x= 1/y^2

But this yielded the wrong answer,

I then re examined the question and tried y^2/x =1

Which I then got y = SQR(X)

subbing into y/3a I got answer E)

not sure what is the correct way to do this. thanks!



hi, u missed a point, y is divided by 3a, i.e y^2 is divided by 9a^2.....
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nadi se roz mitti kat rahi hai....

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Re: The variable x is inversely proportional to the square of the variable [#permalink]

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New post 04 Jan 2017, 06:32
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pmklings wrote:
The variable x is inversely proportional to the square of the variable y. If y is divided by 3a, then x is multiplied by which of the following?

a. 1/9a

b. 1/9a^2

c. 1/3a

d. 9a

e. 9a^2



Here is a post on inverse variation: the-variable-x-is-inversely-proportional-to-the-square-of-the-variable-205761.html

Now read the following:

x * y^2 = k

x' * (y/3a)^2 = k = x * y^2

x' * (y^2)/9a^2 = x * y^2

x' = x * 9a^2

Answer (E)
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Re: The variable x is inversely proportional to the square of the variable [#permalink]

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New post 18 Jan 2017, 15:42
VeritasPrepKarishma wrote:
pmklings wrote:

Here is a post on inverse variation: the-variable-x-is-inversely-proportional-to-the-square-of-the-variable-205761.html

Now read the following:

x * y^2 = k

x' * (y/3a)^2 = k = x * y^2

x' * (y^2)/9a^2 = x * y^2

x' = x * 9a^2

Answer (E)


Sorry I don't understand, Can anyone explain. Thanks
The variable x is inversely proportional to the square of the variable y ???
Why x*y^2 ??

I wrote as \(\frac{1}{x}\) = y^2
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Re: The variable x is inversely proportional to the square of the variable [#permalink]

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New post 18 Jan 2017, 17:36
VeritasPrepKarishma wrote:


VeritasPrepKarishma Did you man to post another link? This is the problem being discussed.
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Re: The variable x is inversely proportional to the square of the variable [#permalink]

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New post 18 Jan 2017, 18:09
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Even i selected B as the answer.

When the question says "x is multiplied by" it seems to ask for the constant that is multiplies X to keep the inverse proportion valid, but it really is asking for by what factor does the new value of X differ from the previous one which is Option E.

xy^2 = K or X = K/y^2

Xy^2/9a = K

=> X(new) = 9a (K/y^2) from above = 9a(X(old)) = X(old) * 9a
i.e X (new) = X(old) * 9a => Option E

I have this problem of not understanding/misinterpreting the question sometimes :'( :'(
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Re: The variable x is inversely proportional to the square of the variable [#permalink]

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New post 19 Jan 2017, 00:56
raeann105 wrote:
VeritasPrepKarishma wrote:


VeritasPrepKarishma Did you man to post another link? This is the problem being discussed.


Oops! Yes, it is this one: https://www.veritasprep.com/blog/2013/0 ... inversely/
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Re: The variable x is inversely proportional to the square of the variable [#permalink]

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New post 19 Jan 2017, 01:00
kanusha wrote:
VeritasPrepKarishma wrote:
pmklings wrote:

Here is a post on inverse variation: the-variable-x-is-inversely-proportional-to-the-square-of-the-variable-205761.html

Now read the following:

x * y^2 = k

x' * (y/3a)^2 = k = x * y^2

x' * (y^2)/9a^2 = x * y^2

x' = x * 9a^2

Answer (E)


Sorry I don't understand, Can anyone explain. Thanks
The variable x is inversely proportional to the square of the variable y ???
Why x*y^2 ??

I wrote as \(\frac{1}{x}\) = y^2


You can write it as

k/x = y^2
which is the same as k = x * y^2

Note that it is not necessary that constant is 1. k could take any value. So when you equate, you need to use k, not 1.
Check out the post for which the link is given above.
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Re: The variable x is inversely proportional to the square of the variable [#permalink]

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New post 19 Jan 2017, 02:21
kanusha wrote:
VeritasPrepKarishma wrote:
pmklings wrote:

Here is a post on inverse variation: the-variable-x-is-inversely-proportional-to-the-square-of-the-variable-205761.html

Now read the following:

x * y^2 = k

x' * (y/3a)^2 = k = x * y^2

x' * (y^2)/9a^2 = x * y^2

x' = x * 9a^2

Answer (E)


Sorry I don't understand, Can anyone explain. Thanks
The variable x is inversely proportional to the square of the variable y ???
Why x*y^2 ??

I wrote as \(\frac{1}{x}\) = y^2


Hi ,

The variable x is inversely proportional to the square of the variable y ???

The above statement can be written as follows:

\(x \propto \frac{1}{y^{2}} = \frac{k}{y^{2}}\) , where \(k\) is a proportionality constant.
or you can wtite it as
\(x y^{2} = k\).

Hope this helps.
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Re: The variable x is inversely proportional to the square of the variable [#permalink]

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New post 02 Mar 2018, 17:54
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Re: The variable x is inversely proportional to the square of the variable   [#permalink] 02 Mar 2018, 17:54
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