Question

Two activities $A$ and $B$ are to be done in the given sequence. The variation of direct cost $\left(DC\right)$ with possible activity duration $\left(T\right)$ (in days) is indicated for each activity as follows.
$\begin{array}{ccccccc}T& & DC& & T& & DC\\ 8& & 12& & 10& & 15\\ 7& & 14& & 9& & 17\\ 6& & 17& & 8& & 19\\ 5& & 21& & 7& & 21\end{array}$


What is the increase in total direct cost between a combined duration of 16 days and 13 days?

• A. 5
• B. 7
• C. 8
• D. 6

Answer 1

The correct option is B 7

Normal time for both activities
$\text{for}A,T_{NA}=8$ days
$\text{for}B,T_{NB}=10$ days

Either of the activities can be crashed and the tabular representation of crashing is as follows:
$\begin{array}{cccc}\text{Activity}& \text{Direct}\text{costs}& \text{Total time}& \text{Total cost}\\ AB& AB& & \\ 810& 1215& 18& 27\\ 710& 1415& 17& 29\\ 79& 1417& 16& 31\\ 78& 1419& 15& 33\\ 77& 1421& 14& 35\\ 67& 1721& 13& 38\\ 57& 2121& 12& 42\end{array}$

Increase in direct cost between a combined duration of 16 days and 13 days = 38 - 31 =7