A graph of $Q = 16 e^{-0.12 t}$ is given in the figure. (a) What is the initial value of $Q$ (when $t = 0$)? $Q(0) =$  help (numbers) (b) Use the graph to estimate the value of $t$ when $Q = 4$. $t \approx$  help (numbers) (c) Use logs to find the exact value of $t$ when $Q = 4$. $t =$  help (logarithms)

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