Chapter 12 - Section 12.3 - Exponential Functions - Exercise Set - Page 862: 42

a) 398.1 parts per million b) 429 parts per million

a) $2015-2000=15$ $y=369.4*(1.005)^t$ $t=15$ $y=369.4*(1.005)^t$ $y=369.4*(1.005)^15$ $y=369.4*1.07768$ $y=398.096$ $y=398.1$ b) $2030-2000=30$ $y=369.4*(1.005)^t$ $t=30$ $y=369.4*(1.005)^t$ $y=369.4*(1.005)^30$ $y=369.4*1.1614$ $y=429.0212$