In an alloy, the ratio of copper and zinc is 5 : 2. If 1.250kg of zinc is mixed in 17kg 500g of alloy, then the ratio of copper and zinc in the alloy will be -

Explanation:-

Quantity of copper in 17.5kg of alloy $$\eqalign{ & = \left( {17.5 \times \frac{5}{7}} \right){\text{kg}} \cr & = 12.5{\text{kg}}. \cr}$$ Quantity of zinc in 17.5kg of alloy $$\eqalign{ & = \left( {17.5 \times \frac{2}{7}} \right){\text{kg}} \cr & = 5{\text{kg}}. \cr & \therefore {\text{Required ratio}} \cr & = 12.5:\left( {5 + 1.25} \right) \cr & = 12.5:6.25 \cr & = 2:1. \cr}$$