Is x = 1/y?

jjjinapinch wrote:Is x = 1/y?

(1) xy = 1
(2) 1/(xy) = 1

Official Guide question
Answer: D

Target question: Is x = 1/y?

Statement 1: xy = 1
This tells us that y does NOT equal 0
So, if we take xy = 1 and divide both sides by y, we get x = 1/y
PERFECT, this is exactly what we are looking for.
Since we can answer the target question with certainty, statement 1 is SUFFICIENT

Statement 2: 1/(xy) = 1
This tells us that x and y do NOT equal 0
So, we can take 1/(xy) and multiply both sides by x to get 1/y = x
Also PERFECT!
Since we can answer the target question with certainty, statement 2 is SUFFICIENT

Answer: D

Cheers,
Brent

Hi All,

We're asked if X = (1/Y). This is a YES/NO question. We can answer it by 'rewriting' the question and the given information so that the various equations appear in the same 'format.' To start, we can rewrite the question by multiplying both sides by Y --- this lead to "Does (X)(Y) = 1?"

1) (X)(Y) = 1

Fact 1 tells us exactly what we need to know. Since (X)(Y) = 1, the answer to the given question is ALWAYS YES.
Fact 1 is SUFFICIENT

2) (1)/(X)(Y) = 1

Fact 2 can be rewritten as 1 = (X)(Y)(1) --> 1 = (X)(Y). In that same way that Fact 1 tells us exactly what we need to know about (X)(Y), so does Fact 2 - and the answer to the question is ALWAYS YES.
Fact 2 is SUFFICIENT

Final Answer: D

GMAT assassins aren't born, they're made,
Rich

jjjinapinch wrote: ↑

Mon Jul 24, 2017 9:32 am

Is x = 1/y?

(1) xy = 1
(2) 1/(xy) = 1

Official Guide question
Answer: D

Solution:

Question Stem Analysis:

We need to determine whether x = 1/y.

Statement One Alone:

Dividing both sides by y (since y can’t be 0), we have x = 1/y. Statement one alone is sufficient.

Statement Two Alone:

Multiplying both sides by xy (since xy can’t be 0), we have xy = 1. Since this is the same as statement one and statement one is sufficient, statement two is also sufficient.

Answer: D