1.
A tank, having a capacity of 700 gal, initally contains 10 lb of salt
dissolved in 100 gal of water. At time t = 0, a solution containing 0.5 lb
of salt per gallon flows into the tank at a rate of 3 gal/min and the
well-stirred mixture flows out of the tank at a rate of 2 gal/min.
(1). How much time will elapse before the tank is filled to capacity?
(2). What is the salt concentration in the tank when it contains 400 gal
of solution?
(3). What is the salt concentration at the instant the tank is filled to
capacity?
dP P
以下兩題 好像會用到 ─── = 0.1 (1 - ───)P 這個公式
dt 3
2.
Suppose the colony starts with 100,000 indivduals. How long will it take the
pop-ulation to reach 90% of its equilibrium value?
3.
Suppose, after 3 years of existence, the colony population is found to be
2,000,000 individuals. What was the initial population?
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