MATH 222 Quiz: MATH 222 UW Madison Quiz4 ans
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Problem 2 (15 points): mixture problem: a 200-gal tank is half full of distilled water. Since at the beginning, the 200-gal tank is half full, the time to ll this tank is: Let m(t) denote the mass of concentrate in the tank at time t. then we have: m(t + 1) m(t) = {5 0. 5 3 m(t) V (t) is the density of the concentrate at time t. and v (t) = 100 + 2t as we got above. where m(t) We solve this rst-order linear di erential equation by integrating factor:u(t) = e e. Then we have: ln(100+2t) = (100 + 2t) Use unitial condition: m(0) = 0, we have: 0 = 50 + c. Method 2: use (t) as variable. m(t) = 50 + t + 50000(100 + 2t) . Let"s use min as the unit of time. At time t, the volume is:v (t) = 100 + 2t.