waecmaths question:
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?
Option A:
320g
Option B:
420g
Option C:
520g
Option D:
620g
waecmaths solution:
$\begin{align} & \text{Percentage of copper}=(100-65)percent=35percent \\ & 35\text{percent}\to 147g \\ & 65percent\text{ }\to \frac{65}{35}\times 147=273g \\ & \text{Mass of the casting }=147g+273g=420g \\\end{align}$
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