WAEC - Mathematics (2010 - No. 7)
A casting is made up of Copper and Zinc. If 65% of the casting is Zinc and there are 147g of Copper. What is the mass of the casting?
320g
420g
520g
620g
解释
%Zinc + %Copper = 100%
65% + %Copper = 100%
%Copper = 100% - 65% = 35%
%Copper = \(\frac{\text{Mass of % Copper}}{\text{Mass of Casting}}\) x 100%
Mass of Casting = \(\frac{147}{35}\) x 100%
= 420g
65% + %Copper = 100%
%Copper = 100% - 65% = 35%
%Copper = \(\frac{\text{Mass of % Copper}}{\text{Mass of Casting}}\) x 100%
Mass of Casting = \(\frac{147}{35}\) x 100%
= 420g