Quantitative comparison questions offer unique opportunities and challenges. Your job isn't to solve a problem, just to determine whether one quantitiy is greater than another. In addition to all of the general tips and strategies listed above, keep the following in mind when answering quantitative comparison questions:
1) If the quantities are expressed in different forms, make them look alike. Eliminate parentheses and factor out expressions. In geometry formulas, convert a given measurement (such as an area, perimeter or volume) to the formula that it represents.
2) Consider the two columns to be sides of an equality. Whatever you do to one side, do to the other. (The only operations that you cannot do without potentially changing the relationship between the two sides are multiplying and dividing by a negative number.)
3) If the problem includes variables, try substituting numbers to make the relationship clearer. Choose numbers that are easy to work with. Try to find a second set of numbers that will alter the relationships. Make sure the relationship holds for positive numbers, negative numbers and fractions.
4) Choice D is correct in cases when you can demonstrate two different relationships between the columns. If the quantities both contain only numbers, Choice D is never correct.
5) Beware of common traps. One trap is the use of squares: the square root of 25 can be either +5 or -5.
6) Remember your goal: to determine whether one side is larger than another. Stop working on the question the second you have enough information. Do NOT bother doing any additional calculations.