LUANDATO wrote:x and y are two positive integers. D is the greatest common divisor of x and y. Is D > 20?
(1) x is a multiple of 4
(2) y is a multiple of 20
The OA is E.
I don't understand it. Can any expert explain this DS question for me please? Thanks.
(1) x is a multiple of 4
Given x is a multiple of 4, x can be 4, 8, 12, 16, 20, 24, 28, 32, 36, 40...etc. Moreover, we do not have information about y. Insufficient.
(2) y is a multiple of 20
y can be 20, 40, 80, etc. Moreover, we do not have information about x. Insufficient.
(1) and (2) combined:
Case 1: If x = 4 and y = 20, then GCD = 4.
Case 2: If x = 20 and y = 20, then GCD = 20. No unique answer.
Insufficient.
The correct answer:
E
Hope this helps!
-Jay
Download free ebook:
Manhattan Review GMAT Quantitative Question Bank Guide
_________________
Manhattan Review GMAT Prep
Locations:
New York |
Bangkok |
Abu Dhabi |
Rome | and many more...
Schedule your free consultation with an experienced GMAT Prep Advisor!
Click here.
