Quantitative Reasoning: Tip

When comparing column A to column B, there are times when you need to substitute a number for the variable (x or n or whatever) to think about the circumstances in which the expressions have quite different values. For example,

Column A 5x versus Column B 6x


If x is a positive number, column B will always be greater.
If x is zero, column A will be equal to column C.
If x is a negative number, Column A will be greater than column B.

So, in that case, you must say that you do not have enough information to say which column has a greater value.


But, let's look at a different kind of problem:

Column A x - .24 versus Column B x - .23

We are always subtracting more from x in the Column A expression, because .24 is bigger than .23. So, no matter whether what number is substituted for the variable x, Column B's value is always going to be greater than column A's!!