How much of each chemical is needed to make 750 kg of the plant food, if a plant food is to be made from three chemicals and 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?

1 Answer
Mar 31, 2015

1st chemical 50 kg, 2nd chemical 400 kg, 3rd chemical 300 kg

Explanation:

Let a, b, c be the weights of three chemicals, then as per the question

a+b+c=750 and

a+b=60%of 750=75060100=450

Clearly c will be 750450=300 kg

Now ratio of b to c is 4:3, that means

bc=433b=4c

Since c is 300 kg, as calculated above,

3b=3(400)=1200

Hence b=400. Now, since

a+b=450a=450400=50 kg

Thus chemicals a, b, and c in 750 kg of plant food would be 50 kg, 400 kg, and 300 kg.