A chemist has one solution containing 50% acid and a second one containing 25% acid. How much of each should be used to make 10 litres of a 40% acid solution?

Answer

50 % solution = 6 litres, 25 % solution = 4 litres

Explanation

Let x litres of 50 % solution be mixed with y litres of 25% solution.
Then, ` x + y = 10 " " `… (i)
and , ` ( 50 x )/(100) + ( 25y)/(100) = ( 40 xx 10)/(100) rArr 2x + y = 16." "`… (ii)