Question

A health clinic uses a solution of bleach to sterilize petri dishes in which cultures are grown. The sterilization tank contains 60 gal of a solution of 4% ordinary household bleach mixed with pure distilled water. New research indicates that the concentration of bleach should be 8% 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 1

2.5 gallons that are removed and 2.5 gallons of bleach that are added

Step-by-step explanation:

Let's take as

x = amount of the original solution that is removed and the amount of bleach to add.

The equation for the amount of lye is equal to:

0.04*(60 - x) + x = 0.08*(60)

2.4 - 0.04x + x = 4.8

-0.04x + x = 4.8 - 2.4

0.96x = 2.4

Clearing x:

x = 2.4/0.96

x = 2.5 gallons that are removed and 2.5 gallons of bleach that are added