For a+b to be even, either both a and b must be even or both a and b must be odd. Since we will be choosing 5 possible "a" numbers and 5 possible "b" numbers, the total number of possibilities will be 25. The question is: How many of those will fit the above criteria? We have 3 w...

Here's another solution that some may find easier. We have 6 empty seats and three couples. How many people can sit in the first seat? 6 people -- any of the people waiting to be seated. However, once that happens, the person sitting next to him or her must be the other half of the couple, so we hav...

The process of elimination is pretty straightforward. Let's run down the list. A. In all moderately dim light in which people without the disorder can read large print, people with the disorder cannot read such print. It does not say that. In fact, it says that people with this disorder have normal ...

Imagine that we have 6 marbles in our hand and 4 empty bowls. We select one of the marbles. Where can we place it? In any of the 4 bowls. So we have 4 choices. Now we have the second marble in our hand. Where can we place it? Again, in any of the 4 bowls. So we have 4 more choices. The same goes for...

The easiest solution is to assume that at the time both pumps started working on the basement, there were 12 units of water in the basement. This is the least common multiple of 4 and 3. Accordingly, the basement had 24 units of water in it when it was full. Since the pump X evacuated 12 units of wa...

Critical reasoning questions are best handled by reading the question first. In this case, we find that the administrators like a certain criterion for eliminating workers. Our job is to show that this criterion is bad. Upon reading the text, we discover that the criterion is to eliminate those work...

This is an extremely controversial question drawn from the Manhattan GMAT CAT tests. Supposedly (A) is the best answer. The reasoning expressed by MGMAT instructors is that (A) offers an alternate explanation for the decrease in profit margins. Supposedly, increased competition is what is really cau...

Statement 1 tells us that the number may be 111 or 111,111 or even 111,111,111. If you know the divisibility rules for 3, then you will know that each of these numbers is divisible by 3. To determine whether a number is divisible by 3, add up the unit digits. If the result is divisible by 3, then th...