A tank contains 50 gallons of a solution composed of 85% water and 15% alcohol. A second solution containing half water and half alcohol is added to the tank at the rate of 4 gallons per minutes. At the same time, the tank is being drained at the same rate. Assuming that the solution is stirred constantly, how much alcohol will be in tank after 10minutes?

The mass of all carbon dioxide in the atmosphere is currently 3,208 GT (gigatonnes) CO2. Last year, annual global emissions were 37 GT CO2/year. How many more orders of magnitude is the total mass of CO2 in the atmosphere compared to last year's annual global emissions of CO2? 0000 2 6 10 5

Initially a tank contains 10 liters of pure water. Brine of unknown (but constant) concentration of salt is flowing in at 1 liter per minute. The water is mixed well and drained at 1 liter per minute. In 20 minutes there are 15 grams of salt in the tank. What is the concentration of salt in the incoming brine?

400 gallons of pesticide is accidentally spilled into a lake and uniformly mixes with the water. The volume of the lake including the pesticide is 108 gallons. A river flows into the lake bringing 5,000 gallons of fresh water per minute, and the uniform mixture spills over the dam at the same rate. How long, in minutes, will it take to reduce the pesticide in the lake to a safe level of 1 part per million gallons? (Round your answer to the nearest minute.)