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Is x% of x% of y equal to x% less than y ? (1) x(x + 100) =

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asmit123
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Is x% of x% of y equal to x% less than y ? (1) x(x + 100) = [#permalink] New post   16 May 2011, 21:13
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57% (02:15) correct 43% (02:31) wrong based on 35 sessions
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Is x% of x% of y equal to x% less than y ?

(1) x(x + 100) = 10,000
(2) y(y + 1) = 1

OPEN DISCUSSION OF THIS QUESTION IS HERE: is-x-of-x-of-y-equal-to-x-less-than-y-1-x-x-96204.html

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A
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Re: Is x% of x% of y equal to x% less than y ? (1) x(x + 100) = [#permalink] New post   16 May 2011, 23:33
equation is

[x^2/10000] * y = (1- x/100) *y

for a particular value of y say y = 1, the equation becomes

x^2 = 10000 - 100x => x(x+100) = 10000

a exactly gives the equation. sufficient.

b y = 1 will give the above equation. The equation has to be solved. Not sufficient.

y = 0 will give the equation to be equal.
Not sufficient.

Clean A.
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Re: Is x% of x% of y equal to x% less than y ? (1) x(x + 100) = [#permalink] New post   17 May 2011, 10:56
how did u get y in equation 1 ?
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Re: Is x% of x% of y equal to x% less than y ? (1) x(x + 100) = [#permalink] New post   17 May 2011, 11:00
Got it... you got it from the question itself
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Re: Is x% of x% of y equal to x% less than y ? (1) x(x + 100) = [#permalink] New post   24 Jun 2011, 15:18
really i dont understand the data question and i also cant understand the solution your guys posted.... why did you consider y=1? what if y is not 1?
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Re: Is x% of x% of y equal to x% less than y ? (1) x(x + 100) = [#permalink] New post   24 Jun 2011, 15:49
asmit123 wrote:
Is x% of x% of y equal to x% less than y ?

(1) x(x + 100) = 10,000
(2) y(y + 1) = 1


Q:
\(Does \hspace{3} \frac{x}{100}*\frac{x}{100}*y=y-\frac{y*x}{100}\)

Simplify:
\(\frac{x^2*y}{10000}=\frac{100y-y*x}{100}\)

\(\frac{x^2*y}{100}=100y-y*x\)

\(x^2*y=10000y-100y*x\)

\(x^2*y+100yx=10000y\)

\(yx(x+100)=10000y\) -----------1

1. x(x+100)=10000
Substituting in equation 1

\(10000y=10000y\)
Sufficient.

2. y(y + 1) = 1
Apparently, we can't reduce the question in this form.
Not Sufficient.

Ans: "A"
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Re: Is x% of x% of y equal to x% less than y ? (1) x(x + 100) = [#permalink] New post   24 Jun 2011, 17:06
given expression can be re - written as follows

y (x^2-100x-10000) =0?

=> y=0? or (x^2-100x-10000) =0?


1. Sufficient

as (x^2-100x-10000) =0

2. Not sufficient

we know y is not equal to 0. but we dont know anything about x to find out (x^2-100x-10000) =0 or not.

Answer is A.
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Re: Is x% of x% of y equal to x% less than y ? (1) x(x + 100) = [#permalink] New post   09 Oct 2011, 00:26
Is x% of x% of y equal to x% less than y ?

(1) x(x + 100) = 10,000
(2) y(y + 1) = 1

OA is
Show Spoiler
A


Have a stupid doubt about this one. But before that, please have a go at the question. Thanks!
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Re: Is x% of x% of y equal to x% less than y ? (1) x(x + 100) = [#permalink] New post   09 Oct 2011, 10:10
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A is sufficient.

This one seems straight from TGM (Jeff Sackmann)

Ques asks following
X/100 (XY/100) = Y - XY/100

=> X^2Y/10000 = Y(1 - X/100)
=> X^2/10000 = (100 - X)/100
=> X^2/100 = 100 - X
=> X^2 = 10000 - 100X
=> X^2 + 100X = 10000
=> X(X + 100) = 10000 (This is what is been asked)

A. Absolutely Sufficient
B. NOT SUFFICIENT
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Re: Is x% of x% of y equal to x% less than y ? (1) x(x + 100) = [#permalink] New post   09 Oct 2011, 19:59
On simplifying the question stem, we get y(x2 + 100x – 10,000) = 0.

Hence, the answer to the prompt question is affirmative if either x2 + 100x – 10,000 = 0 or y = 0.

A>> follows that X(X + 100) = 10000.
Putting this value in above equation we get,
>y(10000 – 10,000) = 0.
>y(0) = 0

For above to hold, y should be a determinate number. So, y cant be 1/0 (for example)
But A does not gives any information about Y.

So do we assume that Y is real in option A..
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Re: Is x% of x% of y equal to x% less than y ? (1) x(x + 100) = [#permalink] New post   03 Feb 2016, 20:12
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Re: Is x% of x% of y equal to x% less than y ? (1) x(x + 100) = [#permalink]
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