Problem 6. (15pts) In a sequel to the famous animated movie "Madagascar," a ship of animals that escaped from San Diego Zoo crashes on an exotic island. 1,000 animals survive the crash and come out on the island to have fun. An unknown love virus attacks the unsuspecting animals. The epidemic spreads at a rate jointly proportional to the number of animals in love and the number of animals not in love. Instantaneously, 20 animals fall in love at the very beginning. In 10 hours, 400 animals are in love. How long will it take for 60% of the animals to fall in love? Explain, if need be, in words, and include all the calculations supporting your solution. You are not expected to produce a final answer in decimals, but you must simplify your answer as much as possible