Question 341600
The sterilization tank contains 80 gal of a solution of 4% ordinary household
 bleach mixed with pure distilled water.
 New research indicates that the concentration of bleach should be 7% for
 complete sterilization.
 How much of the solution should be drained and replaced with bleach to increase
 the bleach content to the recommended level?
;
Let x = amt of original solution removed and amt of pure bleach to be added
:
Amt of bleach equation:
:
.04(80 - x) + x = .07(80)
:
3.2 - .04x + x = 5.6
:
-.04x + 1x = 5.6 - 3.2
:
.96x = 2.4
:
x = {{{2.4/.96}}}
x = 2.5 gal removed and 2.5 gal of bleach added
:
:
Check solution in original equation
.04(80 - 2.5) + 2.5 = .07(80)
.04(77.5) + 2.5 = 5.6
3.1 + 2.5 = 5.6