Experts Help Needed: Comparison Tested to this Degree?

This is a question from the 3rd Ed. Aristotle SC Prep. Please explain the difference in the below 2 cases, and whether the GMAT will test it to such a degree: The performance of the iron and steel industry this year has been better than that of any other year. The correct answer is: The performance ...

Integer Digit Problem

This was a real GMAT problem from an old GMAT Test Paper exam. How many integers between 324,700 and 458,600 have tens digit 1 and units digit 3? a) 10,300 b) 10,030 c) 1353 d) 1352 e) 1339 E is the correct answer. Could someone explain how one would do this problem in under 2 minutes? Thanks.

Any two numbers that multiply to zero means that one of those numbers is 0. Any number plus 0 and has a sum of 0 means that both numbers must be zero, because any non-zero number plus zero cannot possibly equal zero. How is it possible that B, or A for that matter, could be anything but 0? You keep...

Finally figured it out. The correct answer is choice B. AB = A+B - AB, which also means 2AB = A+B Given that AB = 0, then we can say that 2AB - AB = AB = A+B Since A+B = AB, then of all the answers given, B cannot be which value. The correct is B CANNOT be 1. Why? Since A+B = AB, when B=1, then A+1=...

A 700+ Problem

For any numbers A and B, AB = A+B - AB. If AB = 0, which of the following CANNOT be a value of B?

a) 2

b) 1

c) 0

d) -1

e) -3/2


Do you recommend plugging in the answer choices once you narrow down that -A = B? What's the most efficient way of solving this problem? Correct answer is B

I bought GMAT Test Papers (old GMAT exams) through mba.com. Each exam provides only correct answers, but no explanations. I was just wondering if anyone can get D, since each time I resolve it, I get C.

An Old GMAT Test Question: Rates & Work Problem

This was a real GMAT question, but I only have the correct answer, no explanation: I got C, but the correct answer is D. Can anyone explain to me why? Question: Working alone, printers X,Y, Z can do a certain printing job, consisting of a large number of pages, in 12, 15, and 18 hours, respectively....