Question

A mixture of milk and water contain 80 % milk.X litre of mixture is taken out and replaced with water.Find the value of x if final concentration of mik in mxtre is 50 % and initil qunity of mixture is 80l.

Answer 1

Answer:

Suppose x litres of water is required

In 100 lit of the mixture, there is 80 lit of milk and 20 lit of water. Therefore in 50 lit, quantity of milk=40 lit and quantity of water= 10 lit( assuming that milk does not contain water).

On addition of extra water, quantity of water becomes [10+x] lit. Therefore the fraction of water in the mixture becomes [10+x]/[50+x]. The new % of water becomes [10+x]/[50+x]. 100%

i.e. [10+x]/[50+x]. 100%=50%

or, [10+x]/[50+x]. 100 = 50

or, [10+x]/[50+x].2 =1

or, 20+2x=50+x

or, 2x-x=50–20

or x=30

therefore quantity of water to be asses is 30 lit