Correct answer is A because a “Lead” provides acceleration to the Successor Activity with Finish to Start (FS) relationship. Successor starts 15 days before Predecessor finish.
Suppose the Building Construction work need 40 days. and Land Scaping need 30 days.
In normal process, The building will be completed first within 40 days and then Land Scaping will take 30 days.Total Time will be 40+30=70 days.
But Applying Lead time for Land Scaping...The task will start 15, Total workdays prior and thereby overlap the construction work for 15 days. So, total time will be
40+15(30-15)=55 days. So it is Finish to start 15. That means Building completion task finishes and prior to finish that task Land Scaping start..
Based on the description you gave "Building completion has to be PRECEDED by the landscaping" I would have selected answer "A. FS with 15 days Lead" because FS with a lead makes the second task start earlier.
Have you contacted the original question author and asked for an explanation?
i had assumed FS because finish of landscaping before finish of building
But this is a 15 day delay so i had chosen C but the answer is A a 15 day lead
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