In the Critical Path Method $(CPM)$, the cost-time slope of an activity is given by

1. $\dfrac{\text{Crash Cost – Normal Cost}}{\text{Crash Time}} \\$
2. $\dfrac{\text{Normal Cost}}{\text{Crash Time – Normal Time}} \\$
3. $\dfrac{\text{Crash Cost}}{\text{Crash Time – Normal Time}} \\$
4. $\dfrac{\text{Crash Cost – Normal Cost}}{\text{Normal Time – Crash Time}}$