Question

The landscaper pours 200 gallons of herbicide in a pond. The herbicide degrades 10% each week. The landscaper will put another dose in the pond when the herbicide level drops below 50 gallons. In about how many weeks will he need to add more herbicide?

Answer 1

7.5-8 weeks is your answer. 10% of 200 is 20. Then do 150 divided by 20 and you get your answer. Technically it's 8 because it says lower than 50 it would be at 50 at 7.5 weeks.