Chapter 4 - Exponential Functions - 4.5 The Number e - Exercises and Problems for Section 4.5 - Exercises and Problems - Page 173: 15

a) $Q=8(1.12)^t$, $24.847$ b) $Q=8 e^{0.12 t}$, $26.561$

(a) Since the growth rate is not continuous, we have $Q=8(1.12)^t$. At $t=10$ we have $Q=8(1.12)^{10}=24.847$. (b) Since the growth rate is continuous, we have $Q=8 e^{0.12 t}$. At $t=10$ we have $Q=8 e^{0.12(10)}=26.561$.