Chapter 1, Equations and Graphs - Section 1.10 - Modeling Variation - 1.10 Exercises - Page 165: 36

(a) $C=kpm$ (b) $C=\frac{1}{8}pm$ (c) \$57500

(a) Since $C$ is jointly proportional to $p$ and $m$, we have: $C=kpm$ (b) We are given: $C=60000$, $p=120$, and $m=4000$. So we have: $60000=k*120*4000$ $k=\frac{1}{8}$ Therefore: $C= \frac{1}{8}pm$ (c) We are given: $p=92$ and $m=5000$, so we have: $C= \frac{1}{8}*92*5000=\$ 57500$