Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.

Is the length of a side of square S greater than the length of a side of equilateral triangle T ?

(1) The sum of the lengths of a side of S and a side of T is 22.

(2) The ratio of the perimeter of square S to the perimeter of triangle T is 5 to 6.

In general, when you suppose a:b=2:3 when it comes to ratio, you don't know how big 'b' is but you know that b>a. That is, you can compare a size with the ratio. Also, when one con is number and the other con is ratio(percent), percent is most likely to be an answer.

In the question, it asks if the length a side of square is greater than the length of a side of equilateral triangle. In 2), the question asks the ratio. So, suppose the sum of the lengths of a side of square 5k and the sum of the lengths of a side of equilateral triangle 6k. Then the length of one side of square is 5k/4=1.25k and the length of one side of equilateral triangle is 6k/3=2k, which is 1.25k<2k. So, it is no and sufficient. Therefore, the answer is B. Just like this question, when one con is number and the other conis ratio, you have to pay attention to ratio.

from con 1) and con 2), if one of the conditions is given by numbers and the other is given by ratio (percent,fraction), then the condition with ratio (percent,fraction) value has higher chance of being the answer.

_________________

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.

Find a 10% off coupon code for GMAT Club members.

“Receive 5 Math Questions & Solutions Daily”

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

See our Youtube demo