GloryBoy92 wrote:
Hi Guys,
I'm struggling to choose between questions C and E on Data Sufficiency. I do not have a systemic way of arranging my workings and often get confused once I narrow down the answer between C or E.
Example:
If x and y are greater than 0, is x = 1 ?
(1) x/y = 1
(2) xy = 1
I begin using the variable/picking numbers approach
(1) X and Y could be 2 and 2, 0.5 and 0.5 or 1 and 1 (Insufficient) ELIMINATE A and D
(2) X and Y could be 1 and 1, 2 and 0.5 or 3 and 3 (Insufficient) ELIMINATE B
That was easy right.
The hard part is COMBINING the 2 statements. how do I do this systemically, with as much structure as possible and with avoiding confusion. I've noticed that when I get the answer down to C and E, I almost always get it wrong for these types of questions, I just cant figure it out. PLEASE HELP!!
Hi Glorybou92,
As long as you use algebra, when combining the statements, you should not have a problem. So, we have:
1) x = y
2) xy = 1
Substituting, we have:
x^2 = 1
x = 1 or x = -1
Since we are originally given that x is greater than zero, we see that x must be 1.