ps17

ket_gmat · Posted: Sun Oct 12, 2008 1:52 am Post subject: ps17

hi please solve this attached problem.

mental · Posted: Sun Oct 12, 2008 2:58 am Post subject:

Imo C

whats the OA?

raunekk · Posted: Sun Oct 12, 2008 3:39 am Post subject:

i more for C

if v take C=1/2
D= 2/3

ket_gmat · Posted: Sun Oct 12, 2008 4:58 am Post subject:

mental · Posted: Sun Oct 12, 2008 5:09 am Post subject:

.
0 < 1 - c/d < 1
subtract 1 from all sides

-1 < -c/d < 0

multiply all sides by d............as we know d>0, it wont affect the signs or inequality

-d < -c < 0

multiply all sides by -1...........as you do that the signs would change

d > c > 0

this means c > 0 and c< d

you can see I and II will always be true..a direct deduction from ineuality

for III you can prove it wrong by using any two +ve fractions, whose sum is less than or equal to 1

raunekk · Posted: Sun Oct 12, 2008 6:28 am Post subject:

cramya · Posted: Sun Oct 12, 2008 7:25 am Post subject:

Given d > 0 and 0 < 1 - c / d < 1

I) c > 0 - This (I) must be true because if either c is o and c is negative then the inequality would be false.

Eg: c=0

0 < 1 - 0 / d < 1 i.e 0<1<1 - Not possible

c= -ve

0<1+somevalue<1 - Not possible

2) 0 < 1 - c / d < 1

Add c/d to all sides of the inequality

c/d<1<1+c/d

II must be true (proved above)

3)Consider fractional values for c and d

Let c=1/4 d=1/2

0<1- (1/4) / (1/2) < 1
0< 1/2<1

c^2+d^2 < 1 and not > 1

Therefore C) Hope this helps!

OA?