On decreasing the radius of a cirlce by 30% its area is decreased by

On decreasing the radius of a circle by 30% its area is decreased by

On increasing the price of TV sets by 30%, their sale decreases by 20%, what is the effect on the revenue receipts of the shop?

If the side of an equilateral triangle is decreased by 20%, its area is decreased by (a) 36% (b) 40% (c) 60% (d) 64%

How many percentage of the volume of a right circular cone will be increased or decreased if its radius of base is increased by 20% and its height is decreased by 10% ?