The mass of 5/6 dm³ of copper is equal to 2 1/7 kg. Find the mass of 2 5/8 dm³ of copper.

Let’s make a proportional relationship.

The volume of 5/6 dm3 is equal to the mass of 2 1/7 kg,

The volume of 2 5/8 dm3 is equal to x kg.

Means:

5/6 – 2 1/7,

2 5/8 – x.

Hence: 5/6 * x = 2 1/7 * 2 5/8.

For a further solution, let’s translate the mixed numbers:

2 1/7 = (2 * 7 + 1) / 7 = (14 + 1) / 7 = 15/7,

2 5/8 = (2 * 8 + 5) / 8 = (16 + 5) / 8 = 21/8.

5/6 * x = 15/7 * 21/8.

5/6 * x = (15 * 21) / (7 * 8).

5/6 * x = 315/56.

x = 315/56 / 5/6 = 315/56 * 6/5 = (315 * 6) / (56 * 5) = 1890/280 = 6.75 kg.

Answer: The mass is 6.75 kg.