A 200 kg tin / copper alloy contains 60% copper. How much pure tin must be added to obtain

A 200 kg tin / copper alloy contains 60% copper. How much pure tin must be added to obtain an alloy containing 40% copper.

1) Determine the initial weight of copper in the alloy.

To do this, multiply the mass of the alloy by the percentage of copper content in it.

Will:

200 * 60% / 100% = 200 * 0.6 = 120 grams of copper.

2) Find the weight of the new alloy.

To do this, we make up the proportion in which we write the new weight as x.

Since we know that in the new alloy, 120 grams of copper is related to 40% of the alloy, we get the ratio:

x / 100% = 120/40%.

40 * x = 120 * 100.

40 * x = 12000.

x = 12000/40 = 300 grams.

3) Find the weight of the tin.

300 – 200 = 100 grams.

Answer:

You need to add 100 g of tin.