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 does he need

Answer 1

see the explanation

Explanation:

Let

x ---> kilograms of cement needed

y ----> kilograms of sand needed

z ----> kilograms of gravel needed

we know that

`x:y:z=1:3:4` ---->
`x+y+z=1+3+4=8`

`x+y+z=480\ kg`

Divide 480 by 8

`480/8=60` ----> scale factor

Multiply the scale factor by the ratio
`1:3:4`

Find out the kilograms of cement needed

`60(1)=60\ kg`

Find out the kilograms of sand needed

`60(3)=180\ kg`

Find out the kilograms of gravel needed

`60(4)=240\ kg`