Question 600396
let
1.5% solution = x ml
25% solution = (1000-x) ml


1.5/100 * x + 25/100 * (1000-x) = 6.5/100 * 1000
0.015x + 0.25*(1000-x) = 65
0.015x + 250 - 0.25x = 65
250 - 65 = 0.25x - 0.015x
185 = 0.235x
x = 185/0.235 = 37/0.047 = 37000/47 ml


so 1.5% solution needed is 37000/47 ml