Question

3. A reservoir contains 600 litres of pure water. Brine (salty water) that contains 0.2 kg/L of salt is added at a rate of 2 L/min. Brine from a second source with 0.05 kg/L of salt is added at a rate of 3 L/min. Assume that the reservoir is instantaneously well-mixed. The reservoir is drained at a rate of 5 L/min. Let Q(t) be the amount of salt (in kg) at time t (in min).
a)set up and sovle the differential equation for Q(t)
I got the function
Q(t) = 66e^(x/120) - 66
it doesn't seem right can anyone please check for me?

Answer 1

correct. i got the same equation :
\[Q(t) = 66\left( 1 - e ^{-t/120} \right)\]

Answer 2

thanks

Answer 3

that isn't the same though

Answer 4

how did you get a negative exponent?

Answer 5

oh I see nvm

Answer 6

ok... :)