If you have 10,000 dollars in the account, at what rate is your money growing? Rate of change = dollars/year
Suppose that you are also withdrawing money from the account at $1,000 per year. What is the net rate of change in the amount of money in the account? Rate of change = dollars/year
(b) Suppose that a water tank contains 100 gallons of salt water and that a salty solution, which contains 20 grams of salt in every gallon, enters the tank at 2 gallons per minute.
How much salt enters the tank each minute? Rate of salt entering = grams/minute
Suppose that initially there are 300 grams of salt in the tank. How much salt is in each gallon at this point in time? Concentration of salt = grams/gallon
Finally, suppose that evenly mixed solution is pumped out of the tank at the rate of 2 gallons per minute. At what rate is the salt leaving the tank? Rate of salt leaving = grams/minute
What is the net rate of change in the amount of salt in the tank? Rate of change = grams/minute
You can earn partial credit on this problem.