Question

Fresh grapes contain 84% water while raisins contain 20% water. How many kg of raisin can be made from 80 kg of grapes?

Answer 1

Let the Number of Kg of Raisins made from 80 Kg of Grapes be : R

Given : Fresh Grapes Contain 84% Water and 16% Fruit Pulp

⇒ 80 Kg Fresh Grapes Contain : $[\frac{16}{100}\times80] = 12.8\;Kg\;Fruit\;Pulp$

As, The Fruit Pulp remains the Same, Both in Fresh Grapes and Raisins :

⇒ Fruit Pulp in Raisins is 12.8 Kg

Given : Raisins Contain 20% Water and 80% Fruit Pulp

⇒ 80% of 'R' Kg of Raisins = 12.8 Kg

⇒ $(\frac{80}{100}\times R) = 12.8$

⇒ 0.8R = 12.8

⇒ $R = \frac{12.8}{0.8} = \frac{128}{8} = 16\;Kg$

⇒ 16 Kg of Raisin can be made from 80 Kg of Fresh Grapes

Answer 2

The weight of non-water in 20 kg of dried grapes (which is 100-20=80% of whole weight) will be the same as the weight of non-water in 80 kg of fresh grapes (which is 100-84=16% of whole weight).

So if x is the weight of resin, by mass balance we get: x*0.8 = x*0.16 --> x = 64.

Hence 64 kg of resins will be available from 80 kg of grapes.