Problema Solution
how much pure alcohol must be added to 400ml of a 15% solution to make its strength 32%?
Answer provided by our tutors
let
x = ml of 100% alcohol (pure alcohol), x>0
the new solution will me x+400 ml and 32% alcohol
100% of x alcohol + 15% of 400 alcohol = 32% of (x+400) alcohol
1.00*x + 0.15*400 = 0.32(x+400)
x + 60 = 0.32x + 128
x - 0.32x = 128 - 60
0.68x = 68
x = 68/0.68
x = 100
100 ml of pure alcohol needs to be added.