Bunuel wrote:

On a number line, 0 < A < B, is |20 - A| < |20 -B| ?

(1) A + 20 < 2B

(2) B = 3A

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.

Since we have 2 variables (A and B) and 1 equation, D is most likely to be the answer. So, we should consider each of the conditions on their own first.

Condition 1)

If A = 20 and B = 60, the answer is "yes".

If A = 10 and B = 30, the answer is "no".

Since we don't have a unique solution, condition 1) is not sufficient.

Condition 2)

If A = 20 and B = 60, the answer is "yes".

If A = 10 and B = 30, the answer is "no".

Since we don't have a unique solution, condition 1) is not sufficient.

Conditions 1) & 2)

If A = 20 and B = 60, the answer is "yes".

If A = 10 and B = 30, the answer is "no".

Since we don't have a unique solution, condition 1) is not sufficient.

Therefore, the answer is E.

If the original condition includes “1 variable”, or “2 variables and 1 equation”, or “3 variables and 2 equations” etc., one more equation is required to answer the question. If each of conditions 1) and 2) provide an additional equation, there is a 59% chance that D is the answer, a 38% chance that A or B is the answer, and a 3% chance that the answer is C or E. Thus, answer D (conditions 1) and 2), when applied separately, are sufficient to answer the question) is most likely, but there may be cases where the answer is A,B,C or E.

_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare

The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.

"Only $99 for 3 month Online Course"

"Free Resources-30 day online access & Diagnostic Test"

"Unlimited Access to over 120 free video lessons - try it yourself"