Cast iron contains 3.5% carbon. Find the mass of carbon in 4 tons of cast iron.

Cast iron contains 3.5% carbon of the total mass of the alloy;

Let us denote the total mass of the alloy (cast iron) as M, and the mass of carbon as m;

It is known that M = 4 tons.

Find the mass m of carbon in the total mass of the alloy M (converted to kg. We get M = 4000 kg.).

Decision :
In order to find the mass of carbon, let’s make a proportion.

The mass of carbon is related to the mass of the total alloy (cast iron) as 3.5% to 100%.

m / M = 3.5 / 100. Then from this proportion it follows that 100 * m = M * 3.5.

So m = M * 3.5 / 100; m = 4000 * 3.5 / 100; m = 140 kg.

Answer: The mass of carbon in 4 tons of cast iron is 140 kg or 0.140 tons.