Which one of the following is the amount of time by which the start of an activity may be delayed without delaying the start of a following activity?

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UPSC ESE Prelims (Civil) 20 Feb 2022 Official
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  1. Total float 
  2. Interference float
  3. Independent float
  4. Free float

Answer (Detailed Solution Below)

Option 4 : Free float
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Detailed Solution

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Explanation

Total float: (FT)

It is the amount of time that the completion time of an activity can be delayed without affecting project completion time.

Free float: (FF)

It is the amount of time that the activity completion time can be delayed without affecting the earliest start time of the immediate successor activities in the network.

FF = FT - Sj

Interfering Float: (FIN)

  • The maximum amount by which an activity can be delayed without delaying the project but will cause delay to the Early Start of some following activity
  • It is the difference between total float and free float. It is thus equal to the head event slack.

FIN = FT - FF = Sj 

Where, FT is Total Float, FF is Free float

Independent Float: (FID)

The amount by which an activity can be delayed without delaying the project; even if all predecessors are at Late Finish and all Successors are at Early Start.

FID = FF - Si = FT - Sj - Si 

⇒ FID + S= FF 

i is Tail event Slack

Sj is Head Event Slack 

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