Question:
An alloy of tin and copper consists of 15 parts of tin and 105 parts of copper. Find the percentage of copper in the alloy?
Solution:
Composition of the alloy $=15$ parts of tin $+105$ parts of copper
$=120$ parts
$\therefore$ Percentage of tin $=\frac{15}{120} \times 100$
$=12.5 \%$
Also, percentage of copper $=\frac{105}{120} \times 100$
$=87.5 \%$