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A tank containing 6000L of water drains out in 30 min. The volume V of water in the tank after t min of draining is V=6000(1-t/30)2. Find the instantaneous time rate of change of V after 15 min draining.
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01. V = 6000*[1 - t/15 + (1/900)*t2 ]
02. γ = dV/dt = 6000*[-1/15 + (1/450)*t]
03. γ(t = 15) = 6000*[-1/15 + 15/450] = 6000*(-15/450) = -200 Liters/minute @ t = 15 minutes
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