CPM Homework Help : PC Problem 2-156

Jack makes $\$5/\text{hr}$ for the first six hours on the job and then $\$8/\text{hr}$ after that. Explain why $J(t)$ , Jack’s earnings after he works t hours, is:

$J ( t ) = \left\{ \begin{array} { l l } { 5 t } & { \text { for } 0 \leq t \leq 6 } \\ { 30 + 8 ( t - 6 ) } & { \text { for } t > 6 } \end{array} \right.$ .

Answer:

For the first six hours, Jack makes $\$5/\text{hr}$ , meaning at the end of six hours, he has earned $$30$ . For anytime after six hours (where he has already earned $$30$ ) he adds to the $$30$ by making $\$8$ times the number of hours worked over six hours.