(4) Quantity of lead in alloy 1 = 0 Quantity of lead in alloy 2 = 3/12= 1/4 Since alloys 1 and 2 are mixed inequal quantities, the quantity oflead in alloy 3 will be 50% of thatcontained in alloy 2=
1
2
×
1
4
=
1
8
Value of 1/8 means that alloy 3contains 12.5% of lead.