In measuring the sides of a rectangle, one side is taken 20% in excess and the other 10% in deficit. Find the error per cent in area calculated from the measurement? Choose the correct choice from the following:
A) 12 % deficit	B) 10 % excess	C) 8 % excess	D) 9 % excess	E) none of these

Rationale: since side 1 x side 2 = area therefore , error % in area = ( x + y + xy / 100 ) % = [ 20 - 10 + ( - 10 x 20 ) / 100 ] % or 8 % i . e . , 8 % excess answer : c
Answer: C