Question

Bob the builder is making 480 kg of concrete mix.

Concrete is made by mixing cement, sand and gravel in the ratio 1 : 3 : 4
how much sand does he need ?

Answer 1

The ratio given for cement to sand to gravel is 1 : 3 : 4, and all these make concrete.

Add all the numbers in the ratio:

`1+3+4=8`

Divide the amount of concrete by this number:

`480\text{ kg} /8=60\text{ kg}`

This means that each unit in the ratio represents 60 kg when there is a total of 480 kg of concrete. Now let's look at the given ratio again:

`1:3:4`

The middle number, 3, represents the amount of sand. Multiply this with 60 kg to get the amount of sand needed.

`3 * 60 \text{ kg} = 180 \text{ kg}`

180 kilograms of sand are needed. Let me know if you need any clarifications, thanks! (◕‿◕)

~ Padoru