Question 693487
 What quantity of 70 per cent acid solution must be mixed with a 15 percent solution to produce 4 mL of a 30 per cent solution?
:
Let x = quantity of 70% solution required
then resulting total amt is 4, therefore:
(4-x) = quantity of 15% solution
:
.70x + .15(4-x) = .30(4)
.70x + .6 - .15x = 1.2
.70x - .15x = 1.2 - .6
.55x = .6
x = .6/.55
x ~ 1.1 liters of 70% solution required
:
:
:
Check this
.7(1.1) + .15(4-1.1) = .3(4)
.77 + .435 = 1.2