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.

Attachment:

a.png [ 4.33 KiB | Viewed 689 times ]
For a circle with center point P, chord XY is the perpendicular bisector of radius AP (A is a point on the edge of the circle). What is the length of chord XY?

(1) The circumference of circle P is twice the area of circle P.

(2) The length of Arc XAY = 2π3 .

If we let Z represent the intersection point between AP and XY, and ZP=r, XP=2r, XZ=sqrt(3)r, there is one variable (r), and 2 equations are given from the 2 conditions; there is high chance (D) will be our answer.

From condition 1, 2(phi)r=2(phi)r^2, r=1. This condition is sufficient,

From condition 2, angle AXP=120 deg, and the length of Arc XAY=2(phi)r(120/360)=2(phi)/3. r=1. This conditions is sufficient as well.

1)=2), so the answer becomes (D).

_________________

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