The product of x and y is a constant. If the value of x is increased by 50%, by what percentage must the value of y be decreased? Select:
A) 50 %
B) 40 %
C) 33 1 ⁄ 3 %
D) 25 %
E) 12 1 ⁄ 2 %

Rationale: "product of x and y = xy if the value of x is increased by 50 % , value of y needs to be = xy / ( 1.5 x ) = 2 / 3 y decrease in value of y = y - 2 / 3 y = 1 / 3 y % decrease in value of y = ( 1 / 3 y ) / y * 100 % = 33 1 ⁄ 3 % answer c"
Answer: C