Question

A plant food is to be made from three chemicals. The mix must include 60% of the first and second chemicals. The second and third chemicals must be in a ratio of 4 to 3 by weight. How much of each chemical is needed to make 750 kg of the plant food?

Answer 1

First chemical `50` kilograms, second `400` kilograms and third `300` kilograms to make`750` kilograms of plant food.

Explanation:

Let the three chemicals be `x,y` and `z` kilograms (in order of first, second and third) and we have

`x+y+z=750` .................(A)

Further as `60%` of `750` is `750xx60/100=450`, we have

`x+y=450` and hence `z=750-450=300`

As `y` and `z` are in ratio `4:3`, if we have `300` kilograms of `z`, we would have `400` kilograms of `y`

and hence `x=450-400=50` kilograms.