BPSC 47th Exam Prelims 2005 Solved Paper

Brass is an alloy made primarily of copper and zinc. The proportions of the copper and zinc are varied to yield many different kinds of brass. Basic modern brass is $67\%$ copper and $33\%$ zinc. However, the amount of copper may range from $55\%$ to $95\%$ by weight, with the amount of zinc varying from $5\%$ to $40\%$