A chemist has one solution which is 50% acid and a second which is 25% acid. How much of each should be mixed to make 10 litres of 40% acid solution.                                                                                                                        (Ans:6L,4L)

Ans:    Let 50 % acids in the solution be x

Let 25 % of other solution be y

Total Volume in the mixture = x + y

A.P.Q:

x + y = 10                                     --------(1)

A.P.Q:

50/100 x  + 25/100y = (40/100) ×10

2x + y = 16    --------(2)

So x = 6 & y = 4