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GMAT symbolism

by Lynn0423 » Sun Apr 01, 2007 4:02 pm
Hello: I;m posting again as I think I posted in the wrong forum.


I encountered a question regarding GMAT symbolism which has me scratching my head a little. The question is:

~x=(x^2+1)/2 ; ~y=3y/2 for all integers x and y. If m=2, ~m is equal to which of the following:

A. 13/8
B. 3
C. 15/4
D. 5
E. 37/2

The answer is D.

for ~x, x is in a cirled and for ~y, y is in a box. For ~m, m is in a box and a circle.

Thanks!
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by Prasanna » Sun Apr 01, 2007 5:21 pm
I am not able to follow the question (and the answer). Can any one please help?

Prasanna
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by jayhawk2001 » Sun Apr 01, 2007 6:47 pm
If I understand the question correctly, we have to compute
~2 based on formula for ~y and then use the result in ~x

So, we have

~2 = 3*2/2 = 3

Using this in ~x, we have (3^2 + 1) / 2 = 5

If you have a snapshot (pictorial representation) of the question,
please send so that we can confirm
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by Lynn0423 » Sun Apr 01, 2007 8:44 pm
Jay,

Sorry, call me thick, but if you put x as equal to 2, solve then sub in for y the equation does not calculate (following the same logic just solving for x first). I don't get it. How does one know when to solve for y first and then x or vice versa? I simply cannot follow your logic.

L.
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Re: GMAT symbolism

by ajith » Sun Apr 01, 2007 8:47 pm
Lynn0423 wrote:Hello: I;m posting again as I think I posted in the wrong forum.


I encountered a question regarding GMAT symbolism which has me scratching my head a little. The question is:

~x=(x^2+1)/2 ; ~y=3y/2 for all integers x and y. If m=2, ~m is equal to which of the following:

A. 13/8
B. 3
C. 15/4
D. 5
E. 37/2

The answer is D.

for ~x, x is in a cirled and for ~y, y is in a box. For ~m, m is in a box and a circle.

Thanks!
Let me re-phase the question to a more mathematical form

f(x) = (x^2+1)/2
g(x) = 3*x/2

Now they are asking for f (g(2))

for this

g(2) = 2*3/2 =3

f(g(2) = f(3) = (3^2+1)/2 =10/2 =5


:idea: :idea:
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by ajith » Sun Apr 01, 2007 8:59 pm
Lynn0423 wrote:Jay,

How does one know when to solve for y first and then x or vice versa? I simply cannot follow your logic.

L.
That depends on whether
a) 2 is in the circle enclosed by the box
b) 2 is in the box enclosed by circle

do the innermost operation first

I will explain in case of a

Do the operation curresponding to circle first because that is inner
Do the outer operation next on the result of first operation.

is it clear?
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by Lynn0423 » Sun Apr 01, 2007 9:25 pm
Ajith, thanks!! I got it! Now I remember the rules of those operations! Thanks. BTW, that question was from Kaplan course book 2006-2007.

Thanks again for your help!

L.
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by Cybermusings » Mon Apr 02, 2007 3:48 am
This one seems simple enough. m is in a circle in a square.

Thus you first have to perform the function of a circle and then the square

Function in a circle = (x^2+1)/2 ; for any integer x

Thus for m=2 it equals (2^2 + 1)/2 = 5/2

Now perform the function of a square

Function in a square = (3y/2)

= 3/2 * 5/2 = 15/4
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