A health clinic uses a solution of bleach to sterilize petri dishes in which cultures are grown. The sterilization tank contains 120 gal of a solution of 4% ordinary household bleach mixed with pure distilled water. New research indicates that the concentration of bleach should be 6% for complete sterilization. How much of the solution should be drained and replaced with bleach to increase the bleach content to the recommended level?

Answer:2.5 galStep-by-step explanation:let be x = galons of solution to be drained and replace with bleachso, we have to substract to the current solution of bleach 0.04*120, x gallons that have a concentration of 0.04 xand also, we have to add the same gallons of bleach to the solution, that is xand have to obtain a final concentration of 0.06*120we can express the problem with the follow equation:0.04*120 - 0.04*x + x = 0.06*120solving the equation for x:4.8+0.96*x=7.20.96*x=7.2-4.80.96*x=2.4x =2.5 gallons