Hey guys,
Love the discussion...just want to clarify a few things here:
0 is an even number. Even means "integer that is divisible by 2", and 0/2 = 0, which means since there is nothing after the decimal point that 0 is even. Shankar is right that the question says positive (and 0 is neither positive nor negative), but since it came up I wanted to clarify.
Statement 2 - consider the set 2, 4, 6, 8, 10. Only two of these are divisible by 4 (4 and 8) but all are even. So statement 2 is not sufficient. We know that 10 of the values are divisible by 4, and therefore even. But even numbers like 2 and 6 that are not divisible by 4 can still be even, and we don't know anything about the 10 numbers that aren't divisible by 4. All could be even or all could be odd.
___________________________________
Now, I'd go A on this one but I'd also be surprised if this one passed the "experimental phase" of the GMAT's testing system. Statement 1 says that 10 of the integers are even, and I think it's reasonable to say that, since the set has been defined at 20 total integers, the others are odd. But statement 1 doesn't say "exactly" 10 integers, so logically you could probably construct an argument that, if all 20 of them are even, you're still not wrong in saying "10 are even". You could quite easily say "Bill Gates has a million dollars" and not be wrong...even though he has considerably more than just a million.
So my hypothesis on this one is that it's written to elicit the answer A, but were it in the experimental phase of the official GMAT enough "high ability" users would pick E that they'd have to investigate the question and throw it out. That "10 but not necessarily EXACTLY 10" logic isn't the GMAT's typical style on Data Sufficiency...it's a lot more LSAT or Philosophy than GMAT.
Brian Galvin
GMAT Instructor
Chief Academic Officer
Veritas Prep
Looking for GMAT practice questions? Try out the Veritas Prep Question Bank.
Learn More.
