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?

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Answer 1 · 2018-07-03T05:20:46

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

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.