A certain water filtration system can remove 70% of the
contaminants each time a sample of water is passed through it. If the same
water is passed through the system four times, what percent of the original
contaminants will be removed from the water sample?
I know the answer is 99.19 just don't know how to get it
Answers
ALTERNATIVE WATER TREATMENT TECHNOLOGIES A number of water treatment methods that employ simple, low cost technology are available. These methods include straining; aeration; storage and settlement; disinfection by boiling, chemicals, solar radiation; and filtration; coagulation and flocculation; and desalination. The following classification is based on Skinner and Shaw.29 The different methods are presented alphabetically. Aeration can be accomplished by vigorous shaking in a vessel part full of water or allowing water to trickle down through one or more perforated trays containing small stones. Aeration increases the air content of the water, removes volatile substances such as hydrogen sulfide, which affect odor and taste, and oxidizes iron or manganese so that they form precipitates which can be removed by settlement or filtration