Complete problems 2.18 and 2.19 in Ch. 2 Exercises section of the textbook attached . Note that #18 shows that activity C can't be crashed at all by showing the crash time and cost to be the same as t

Complete problems 2.18 and 2.19 in Ch. 2 Exercises section of the textbook attached .

Note that #18 shows that activity C can't be crashed at all by showing the crash time and cost to be the same as the normal time and cost.

However, #19 shows that activity E can't be crashed at all by showing the crash time and cost to be "-",

I don't know why the text did this, but they mean the same thing. Maybe it was just to show two different accepted ways of indicating an activity can't be crashed.