Hey Guys
I can't get my mind around this question:
If wx = y, what is the value of xy?
(1) wx2=16
(2) y=4
Note: 2 is an exponent of x
Why is A the correct answer?
Let me know
Many thanks
Lukas
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data suficiency
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lukaswelker
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GMATGuruNY
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Statement 1: wx² = 16If wx=y, what is the value of xy?
(1) wx² = 16
(2) y = 4
Test TWO CASES.
If the value of xy is the SAME in each case, then the statement is SUFFICIENT.
If the value of xy CHANGES, then the statement is INSUFFICIENT.
Case 1: w=4 and x=2, so that wx² = 4*2² = 16
Here:
y = wx = 4*2 = 8.
xy = 2*8 = 16.
Case 2: w=16 and x=1, so that wx² = 16*1² = 16.
Here:
y = wx = 16*1 = 16.
xy = 1*16 = 16.
Since the value of xy is the same in each case, SUFFICIENT.
Statement 2: y=4
No way to determine the value of x.
INSUFFICIENT.
The correct answer is A.
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As a tutor, I don't simply teach you how I would approach problems.
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Brent@GMATPrepNow
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Target question: What is the value of xy?If wx = y, what is the value of xy?
(1) wx² = 16
(2) y = 4
Given: wx = y
Statement 1: wx² = 16
We can rewrite this as (wx)(x) = 16
Now replace wx with y to get: yx = 16
Great, we can conclude that xy = 16
Since we can answer the target question with certainty, statement 1 is SUFFICIENT
Statement 2: y = 4
Not enough information to determine the value of xy
Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT
Answer = A
Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
