Answer
$y=6.349e^{-0.462t}$
Work Step by Step
$(1, 4)$ lies on the curve.
Thus, $$4 = Ce^{k}$$
$(4, 1)$ lies on the curve.
Thus, $$1 = Ce^{4k}$$
Dividing this equation by eq 1 gives, $$e^{3k}=\frac{1}{4}$$
Or,$$ k=-\frac{ln(4)}{3}=-0.462$$
By eq 1 we have $$C=4e^{-k}=4e^{0.462}=6.349$$
So, the function is $$y=6.349e^{-0.462t}$$
