A quick project scheduling riddle…

I will try to post another major blog either tomorrow or the next day. But meanwhile, for those who like posers (as opposed to poseurs!), here is a little problem to solve.

If you think you know the answer, feel free to supply it by clicking on the COMMENT function. Under any circumstances, I will provide the answer at the end of my next blog post.

So here is the circumstance:

We have a project to complete. It consists exclusively of work to be done on a computer: data analysis of a previously-performed study and writing up the results, findings and recommendations.

The project consists of exactly 62 eight-hour days of work effort. None of it can be done in parallel and it must all be done by a single resource who will work and produce for exactly eight hours per day, producing one work day of effort every day. No overtime is allowed.

The work is scheduled to start April 1. But it MUST end no later than May 31..

If it starts April 1, how is it possible to complete the 62 days of effort by the end of May 31?

Fraternally in project management,

Steve the Bajan

24 thoughts on “A quick project scheduling riddle…

    • Hi, Marc. That’s true. But I did say: “exactly 62 eight-hour days of work effort. None of it can be done in parallel and it must all be done by a single resource who will work and produce for exactly eight hours per day, producing one work day of effort every day.”

      I think the “single resource” for only “eight hours per day” constraint makes it sufficiently challenging.

      Obviously, there’s a gimmick.

      Fraternally in project management,

      Steve the Bajan

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  1. Hi Steve
    It is the same as fence posts and fence rails. There is always one more post than rails.
    There are exactly 62 whole working days between 1st April and 31st May in any given year.
    Mike T.

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    • Mike — April still has only 30 days on my calendar. How do you count 61 through the end of May 30?

      I counted the actual days on my calendar. 61 total in April and May.

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      • Bill wrote: “And you can’t use the international date line … that would require overtime.”

        No. Going east across the International dateline moves your calendar back one day. You then use that day to work the remaining 8 hours. No overtime because you are only working eight hours each calendar day.

        Steve

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  2. Steve — only one problem … there is no easy way to go across the international dateline unless you are going to argue that the work is being done shipboard. If I’m doing this work, and you want me to travel from Tonga to American Samoa to finish the work, you’ve got to pay me overtime.

    In addition … my sponsor is going to be a bit upset because I doubt that they have traveled with me, and it’s now June 1 in Tonga.

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    • Hi, Bill. First, why couldn’t all the work be performed on a ship? I specifically chose work — data analysis and writing up of findings — that could be done on a ship. A two-month cruise (from west to east, of course) might be just the ticket for our hardworking data analyst.

      But actually, it wouldn’t even have to be done on a ship. Start and complete all the work in Kamchatka by 4pm on June 1st, fly immediately to Anchorage and submit it before midnight on May 31st. Voila. No overtime. Project completed on May 31st.

      Fraternally in project management,

      Steve the Bajan

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      • Steve — my points were:
        (a) requiring me to fly for work involves overtime.
        (b) working more than 8 hours within a 24 hour period is overtime.
        (c) my sponsor is on the other side of the dateline and will not accept my sophistry.

        But the idea is cute.

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  3. Depends on what the resource constraint is. I assume we are comparing two different things here. We have a machine resource that I assume is the constraint. We only have one machine but we do not have to pay it overtime. We can have multiple people resorces available that could work maybe three 8 hour shifts a day. Am I even close to being on the right track?

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    • Hi, Michael. Thanks for replying. The constraint was intended to be that the project could only be worked on for eight hours a day. While your method would probably work, I really only intended this as a simple riddle. My answer to the riddle is here:

      Answer to the Quick Riddle…

      Steve

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  4. If you start numbering each day of work on 4/1 until 4/30 that would equal 30 making May 1 day 31. Now add 31 days for May and you have 62.

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  5. Option 1: “Single resource” need not be “same resource”, therefore, if we get 3 “single resources” over 3 work shifts, we get 24 hours in just one day. that will be going overboard, if we have 2 months to do it.
    Option 2: MUST end 31st May with a scheduled start of 1st April. It cannot be completed in 61 days (April 1st and May 31st Inclusive) so, start earlier!
    Option 3: Re-estimate effort with a better skilled resource who can do it faster OR a better specced computer (Octacore and stuff? we could ask Nasa for one of their super computers – depends how much you earn for this project)

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  6. HERE IS THE SOLUTION STEVE….. AND I KNOW THIS IS PERFECT. Start your project on the 1st of April 2015 and finish it on the 31st of May 2016. THIS TIME FRAME IS MORE THAN ENOUGH :))))

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