A practice question asks to determine the new date of installation for bike racks if the racks now have a 2-week (calendar day) delay. The original install timeline was April 25 - April 30 (5 days).
I thought the two weeks would be added onto this schedule, making the installation complete on May 14 (5 days + 14 days). Instead, the correct answer was May 9th (14 days total). Why are those 5 days of construction from 4/25-4/30 no longer included in the timeline?
Welcome to the ARE Community, @spinski! Thank you for reaching out with your question.
We actually have an existing thread related to this specific question:
For reference, you can use the search bar on the ARE Community home page to search for key terms. If you are struggling with a topic, there is a good chance someone else is too 
Hope this helps! Let me know if you need further clarification.
Kiara Galicinao, AIA, NCARB
Black Spectacles
Thanks, I reviewed the existing thread, but the answer doesn’t address why the additional 2 weeks wasn’t added onto the original 5 days held for installation.
Hi @spinski,
To reiterate what was mentioned in the previous post, the project schedule reflects bike rack installation only - it does not specify which type of bike rack is being proposed here or what the lead time is. Therefore, we need to determine what effect(s) in-ground bike racks would have on the schedule, if any. Does it align with the proposed installation date or does it push the schedule back?
The RFI indicates that in-ground bike racks have a 6-week lead time (resulting in a schedule change) and surface-mount bike racks have a 4-week lead time (resulting in no schedule change). Therefore, we can assume that the project schedule aligns with using surface-mount. If we use in-mount, the lead time increased by 2 weeks and in turn, pushes the installation back by 2 weeks.
The reason why we do not need to add this original 5 day of installation time to the delay is because it was already factored into the schedule. If we were to use surface-mount bike racks, there would be no schedule change (4 week lead time + 5 days total of installation). If we proceed with the in-ground bike racks, we would be delayed (6 week lead time + 5 days total installation). To consider what the overall effect on the schedule is, we take the difference between these two, which is a total of 2 weeks.
I know it’s super confusing and while simple math is involved, it really is a puzzle. For these types of questions, I recommend drawing a diagram or chart to help you visualize the schedule adjustments and effects.
Let me know if you have any further questions!
Kiara