
Omkar A. answered 03/07/20
NCSU Engineering '23
Since the question is asking for the rate of change, you want to take the derivative of C(t). By the chain rule, the derivative of C(t), dc/dt, is equal to -4.35e^-t
Therefore the rate of change after 3 hours and 5 hours can be calculated by plugging in 3 and 5 for t
C'(3) = -4.35e^-3
C'(5) = -4.35e^-5