gmatmachoman wrote:praveen, how many minutes u took to plug in those numbers..
I took near abt 3.5 minutes...Just wanted to cross check!
I took around 3 mins to type it. So should have done it normally with in 2 minutes.
Numbers for disproving A and B are starightforward.
one set of numbers for C makes us think. ohter set should be easy.
In case we do not wan to plugin:
z is multiple of 20 -> z=20a
y^2 is multiple of 10 means y is multiple of 10 -> y=10b
z^2 is multiple of 5 -> z is multiple of 5. -> 20a is already multiple of 5.
now, yz = 200ab is already multiple of 25.
so possible values for for yz=200,400,600...
among these, some are multiples of 500 and some are not.
hence C is INSUFF.
Cheers!!
"Once you start working on something,
don't be afraid of failure and don't abandon it.
People who work sincerely are the happiest."
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