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| Quantitative Comparison Questions |
Some of the questions in the Quantitative section of the test may be quantitative comparison questions. The Following text will explain you the format and techniques u need to attempt the questions of this format.
Question Format
Such questions consist of two quantities, one in column A and the other in column B. You have to compare the two quantities. The information concerning one or both quantities is presented before them. Only the following four choices will be given:
A. The quantity in column A is greater
B. The quantity in column B is greater
C. The two quantities in both columns are equal
D. The relationship cannot be determined from the information given
And as it is clear from the choices, only one will be correct at one time. Your job is to choose one of them after careful comparison. The following text explains some simple tactics to attempt such questions.
How To Attempt
Whenever you encounter a quantitative comparison question, the following guidelines will help you to find the correct answer quickly.
- If the question involves some variables, replace them with appropriate
numbers. Here are some guidelines in choosing an appropriate number:
- The very best numbers to use are –1, 0 and 1.
- Often fractions between 0 and 1 are useful (e.g. 1/2, 3/4 etc.).
- Occasionally, “large” numbers such as 10 or 100 can be used
- If there is more than one variable, it is permissible to replace each with the same number.
- Do not impose any un-specified conditions on numbers. Choose them randomly.
- Eliminate the choices and choose from the remaining ones. For example If you found the quantities ever equal, the correct choice could never be A or B, so, eliminate A and B.
-
A quantitative comparison question can be treated as an equation or
inequality. Either:
Column A < Column B, or
Column A = Column B, or
Column A > Column B
So, you can perform similar operation on both columns to simplify the problem just as in equations (or inequalities).
Example:
m > 0 and m ≠ 1
m2, m3 - In this example divide both the quantities by m2. This will change column A to 1 and column B to m. Now the comparison is very simple, as we know that m is greater than 0 and cannot be 1. So the relationship is not determinable using the current information. m can be both greater than 1 or between 0 and less than 1.
Example questions with Answers and Explanations
Example 1:
| A student earned a 75 on each of her first three math tests and an 80 on her fourth and fifth tests. | |
| A | B |
| Average after 4 tests | Average after 5 tests |
A. The quantity in column A is greater
B. The quantity in column B is greater
C. The two quantities in both columns are equal
D. The relationship cannot be determined from the information given
Remember you want to know which average is higher, not what the averages are. After 4 tests, the average is clearly less than 80, so an 80 on the fifth test had to raise the average. So the answer is choice (B).
Example 2:
| A | B |
| The time it takes to drive 40 miles at 35 mph | The time it takes to drive 35 miles at 40 mph |
A. The quantity in column A is greater B. The quantity in column B is greater C. The two quantities in both columns are equal D. The relationship cannot be determined from the information given
Once again there is no need for calculation, as the speed in column B is higher than that in column A. It is obvious that it will take less time to travel shorter distance at a greater speed. So the value in column A is larger. The answer is option (A).
Example 3:
| A | B |
| (√20)/2 | 5/√5 |
A. The quantity in column A is greater B. The quantity in column B is greater C. The two quantities in both columns are equal D. The relationship cannot be determined from the information given
Square each column: {(√20)/2}2 = 20/4 = 5 and
(5/√5)2 = 25/5 = 5
So both columns are equal and the answer is choice (C).
Example 4:
| A | B |
| 13/y | 15/y |
To solve this question, subtract 13y from both columns to get 13y − 13y = 0 for column A and 15y − 13y = 2y for column B. As there are no restrictions, 2y can be greater than, less than or equal to 0. So the correct choice is (D).
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