Solution: To save time and improve accuracy on DS questions in GMAT, learn and apply the Variable Approach.
Forget conventional ways of solving math questions. For DS problems, the VA (Variable Approach) method is the quickest and easiest way to find the answer without actually solving the problem. Remember that equal numbers of variables and independent equations ensure a solution.
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https://www.mathrevolution.com/gmat/lesson for details.
Now we will solve this DS question using the Variable Approach.
Let’s apply the 3 steps suggested previously.
Follow the first step of the Variable Approach by modifying and rechecking the original condition and the question.
We have to find the value of ‘x’- where ‘x’ is an integer that lies between 100 and 200
Follow the second and the third step: From the original condition, we have 1 variable (x). To match the number of variables with the number of equations, we need 1 equation. Since conditions (1) and (2) will provide 1 equation each, D would most likely be the answer.
Recall 3- Principles and Choose D as the most likely answer. Let’s look at each condition separately.
Condition (1) tells us that the x is a multiple of 36.
The possible multiples of ‘36’ between 100 and 200 are: 36 * 3 = 108 , 36 * 4 = 144, 36 * 5 = 180.
Thus, the value of ‘x’ is not unique.
The answer is not a unique value; condition (1) alone is not sufficient according to Common Mistake Type 2 which states that the answer should be a unique value.
Condition (2) tells us that ‘x’ is an even multiple of 45
The possible multiples of ‘45’ between 100 and 200 are: 45 * 3 = 135 , 45 * 4 = 180.
In this, even multiple is 180, and thus x = 180.
Thus, the value of ‘x’ is unique.
The answer is a unique value; condition (2) alone is sufficient according to Common Mistake Type 2 which states that the answer should be a unique value.
Condition (2) alone is sufficient.
Therefore, B is the correct answer.
Answer: B
