Question

For a project the following data is given.

$\begin{array}{cccc}\text{Activity}& \text{Duration}& \text{Earliest}& \text{Latest}\\ & \text{(in days)}& \text{Start Time}& \text{Finish Time}\\ 1-2& 2& 0& 11\\ 1-3& 7& 0& 7\\ 1-4& 8& 0& 11\\ 2-5& 3& 2& 14\\ 3-5& 6& 7& 14\\ 3-6& 10& 7& 17\\ 3-7& 4& 7& 16\\ 3-7& 4& 7& 16\\ 4-6& 6& 8& 17\\ 5-7& 2& 13& 16\\ 7-8& 6& 15& 22\end{array}$

The free float for activity 3-7 is____ (in days)

• A. 4
• B. 2
• C. 3
• D. 5

Answer 1

The correct option is B 2

From the dat the figure should be constructed,



$\text{The activity for 3 - 7, EST = 7}$

$\text{EFT = EST + duration}=7+4=11$

$\text{LFT = 16}$

$\text{LST = LFT}-\text{Duration}=16-4=12$

$\text{Total float}=\text{LSR}-\text{EST}=12-7=5$

$\text{Earliest start time of 7 - 8 successor activity = 15}$

$\text{Head event slack}=16-5=1$

$\text{Free float = total float - head event slack}=5-1=4$