If w+z = 28, what is the value of wz?
1) w and z are positive integers.
2) w and z are consecutive odd integers.
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What is wz?
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LulaBrazilia
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Patrick_GMATFix
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(1) is NOT SUFFICIENT since (w,z)=(1,27) will result in a different value for wz than (10,18). (2) must be SUFFICIENT since only one set of consecutive odds can add up to 28 (changing a number will change the sum). The answer is B. I go through the question in detail in the full solution below (taken from the GMATFix App).
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Hi LulaBrazilia,
This DS question can be solved by TESTing Values. Here's how:
We're told that W + Z = 28. We're asked for the value of W(Z).
Fact 1: W and Z are positive integers.
If....
W=1
Z = 27
Then WZ = 27
If...
W=2
Z=26
Then WZ = 52
Fact 1 is INSUFFICIENT
Fact 2: W and Z are CONSECUTIVE ODD integers.
This is a remarkably specific piece of information.
Since W + Z = 28, the ONLY way for W and Z to ALSO be consecutive odd integers is if the 2 numbers are 13 and 15.
13(15) is the same as 15(13), so there's only one possible value for WZ.
Fact 2 is SUFFICIENT
Final Answer: B
GMAT assassins aren't born, they're made,
Rich
This DS question can be solved by TESTing Values. Here's how:
We're told that W + Z = 28. We're asked for the value of W(Z).
Fact 1: W and Z are positive integers.
If....
W=1
Z = 27
Then WZ = 27
If...
W=2
Z=26
Then WZ = 52
Fact 1 is INSUFFICIENT
Fact 2: W and Z are CONSECUTIVE ODD integers.
This is a remarkably specific piece of information.
Since W + Z = 28, the ONLY way for W and Z to ALSO be consecutive odd integers is if the 2 numbers are 13 and 15.
13(15) is the same as 15(13), so there's only one possible value for WZ.
Fact 2 is SUFFICIENT
Final Answer: B
GMAT assassins aren't born, they're made,
Rich
