Question

The ratio for concrete (cement:sand:gravel) is 1:3:4. Chau now needs to make 64 kg of concrete. Determine the mass of cement, sand, and gravel she needs to mix together.

Answer 1

8 kg of cement, 24 kg of sand and 32 kg of gravel

Explanation:

Ratios can be expressed as fractions by getting the sum of all the values:

`1+3+4 = 8`

Then expressing each value as a numerator of the sum:

`(1)/(8) , (3)/(8) , (4)/(8) \text{ which represent cement, sand, gravel respectively}`

Since concrete is a mixture of all of this, we simply find the how much of 64 kg, each fraction represents:

`(1)/(8) * 64 kg = 8 kg \text{ cement} \\\\(3)/(8) * 64 kg = 24kg \text{ sand}\\\\(4)/(8) * 64 kg = 32kg \text{ gravel}`