Question

Concrete consists of $1\frac{1}{2}$ parts of lime, 4 parts of gravel and $2\frac{1}{2}$ parts of sand. Out of 480 kg of concrete; how much is lime ?

Answer 1

Let the amount of lime, gravel and sand in the concrete be $1\frac{1}{2}a,4a,2\frac{1}{2}a$
Given, concrete $=480kg$

$1\frac{1}{2}a+4a+2\frac{1}{2}a=480$

$\frac{3}{2}a+4a+\frac{5}{2}a=480$

$\frac{8}{2}a+4a=480$

$8a=480$

$a=60kg$

So, amount of lime $1\frac{1}{2}a=\frac{3}{2}a=\frac{3}{2}\times 60=90kg$