Reconstruct quantities from their rates
Recover the original quantity from its supplied rate and one measured value
A mixing tank has capacity 500 L
Time t is measured in min. The model is valid only for 0 ≤ t ≤ 5. Q is the volume in litres, and its signed net rate is in L/min
\[Q'(t)=2\]
\[Q(0)=20\]
Find the volume at 4 min