Chapter 4.1, Problem 7E

Reminder Round all answers to two decimal places unless otherwise indicated.

Unit Conversion with Exponential Decay The exponential function $P=300\times {0.86}^m$ gives the amount in parts per million of PCBs in a contaminated site $m\text{months}$ after a cleanup process begins.

a. What is the weekly decay factor? Find a formula that gives the amount $P$ in parts per million $w\text{weeks}$ after cleanup begins. Assume that there are four weeks in each month.

b. What is the yearly decay factor? Find a formula that gives the amount $P$ in parts per million $y\text{years}$ after cleanup begins.