Question

To clean a fish tank, 2/3 cup of disinfectant is needed for every 3 gallons of water. How many cups of disinfectant is needed for 36 gallons of water? (Hint: set up a proportion!)

Answer 1

8 cups disinfectant per 36 gallons of water

Explanation:

Yes, set up an equation of ratios:

2/3 cup disinfectant 3 gallons water 1

-------------------------------- = -------------------------- = -----

x 36 gallons water 12

Cross multiplication yields 12(2/3 cup disinfectant) = 1x, so that:

x = 8 cups

8 cups of disinfectant are needed to make a solution involving 36 cups water.