Question

The type of float which give an idea about the excess time that exists if the preceding activity ends as late as possible and the succeeding activity starts as early as possible
1. Total float
2. Free float
3. Independent float
4. Slack

Answer 1

Correct Answer - Option 3 : Independent float

Concept:

Independent float:

• Independent float is the time by which starting or finishing of an activity can be delayed without affecting the total float of its proceeding and succeeding activity.
• It does not affect start of succeeding activity i.e. following activity.
• It does not affect latest completion of preceding activity.
• It only affects concerned activity.

Mathematically, it is given by:

FID = total float – head event slack – tail event slack

Total float: 
It is the time by which starting or finishing of an activity can be delayed without affecting the schedule completion period of a project. It affects both succeeding and proceeding activities.

Mathematically, It is given by

Ft = LST - EST or Ft = LFT – EFT

EST = Earliest Start time
EFT = Earliest Finish time
LST = Latest Start time
LFT = Latest finish time

Free float: 
It is the excess of ‘available time’ over the activity time when all jobs start as early as possible. In this only proceeding, activity is affected and it is given by:

F_f = F_t - head event slack

Slack time: 
It is the amount of time a task can be delayed before the project finish date is delayed. Thus, the slack is the difference between event times denoting the range within which an event time can vary.

Slack = TL - TE

Positive slack: When TL > TE. It indicates the project is ahead of schedule meaning thereby the excess resources.
Zero slack: When TL = TE. It indicates that the project is going on schedule meaning thereby adequate resources.
Negative slack: When TL < TE. It indicates the project is behind schedule meaning thereby the lack of resources.