In measuring the sides of a rectangle, one side is taken 12% in excess and other 5% in deficit. Find the error percentage in the area calculated from these measurements. Choose the correct answer:
A) 3.5 %
B) 6.4 %
C) 3 %
D) 5 %
E) 2.6 %

Rationale: "say both sides of the rectangle are equal to 100 ( so consider that we have a square ) . in this case the area is 100 * 100 = 10,000 . now , the area obtained with wrong measurements would be 112 * 95 = 10,640 , which is 6.4 % greater than the actual area . answer : b ."
Answer: B