Currency wrote:
Ok, without a doubt my number property skills are my achillies heel when is comes to GMAT quant.
I was reviewing my
error log today. Tell me why my logic is wrong.
95. Is rst=1
(1) rs=1
(2) st=1
I attacked it by rearranging the original equations, dividing both sides by t.
so,
rs=1/tthen sub in rs=1
so, 1=1/t
then cross multiply t=1
Combined with what we already know (rs=1) we have 1*1=1
Therefore, sufficient.
Same logic can be applied to statment 2.
Therefore my answer was D.
OA is actually E and I understand how they got it, but I also fail to see why my strategy was wrong. I feel like I'm probably overlooking some basic rule that governs all equations here but if someone could help me out that'd be great.
Thanks
The highlighted part is the mistake.
The question is asking u to prove that... and you are considering the same as True. This isnt the correct approach.
The Answer E is correct...
Is rst = 1?
S1: rs = 1,
t can be 2 ... then rst is not equal to 1...
t can be 1... then rst is equal to 1...
Hence IN SUFF
S2: st =1 ,
r can be 2 ... then rst is not equal to 1..
r can be 1 .. then rst is equal to 1...
Hence IN SUFF...
combining I and 2...
we can have .. r = 2, s = 1/2, t = 2
Then rst = 2
but we can also have r = 1, s = 1, t =1
Then rst = 1..
Hence E...
Hope this helps!