Data Sufficiency

Que: What is the total number of golf clubs that Paul and Mike have?

(1) Paul has 60 percent more golf clubs than Mike.
(2) Mike has between 9 and 14 golf clubs.

Solution: To save time and improve accuracy on DS question in GMAT, learn and apply 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.

Visit 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 total number of golf clubs that Paul and Mike have

Let us assign a variable: Suppose Paul has p golf clubs and Mike has m golf clubs.

Follow the second and the third step: From the original condition, we have 2 variables (p and m). To match the number of variables with the number of equations, we need 2 equations. Since conditions (1) and (2) will provide 1 equation each, C would most likely be the answer.

Recall 3- Principles and Choose C as the most likely answer. Let’s look at both conditions combined together.

Condition (1) tells us that Paul has 60 percent more golf clubs than Mike and Condition (2) tells us that Mike has between 10 and 15 golf clubs.

=> Converting into equation: p = m + 60%m = 1.6m and 9< m < 14

=> Since m is an integer => m must be 10,11,12,or 13

However,

If m = 10 => p = 1.6m => 1.6 * 10 => 16 can be the number of golf clubs that Paul has (∵ It’s an integer)

If m = 11 => p = 1.6m => 1.6 * 11 => 17.6 cannot be the number of golf clubs that Paul has (∵ It’s a decimal number)

If m = 12 => p = 1.6m =>1.6 * 12 => 19.2 cannot be the number of golf clubs that Paul has (∵ It’s a decimal number)

If m = 13 => p = 1.6m =>1.6 * 13 => 20.8 cannot be the number of golf clubs that Paul has (∵ It’s a decimal number)

=> ∴ Paul has 16 golf clubs and Mike has 10 golf clubs

=> Total number of golf clubs possessed by Paul and Mike: 16 + 10 = 26

The answer is unique, so the conditions combined are sufficient, according to CMT 2 - there must be only one answer.

Both conditions together are sufficient.

Therefore, C is the correct answer.

Answer: C