I just posted the answers, with explanations, to last weekend’s PM Puzzler on my blog. They're here [1].
If you haven’t tried this PM Puzzler yet, just click on the BLOG tab and scroll down past the answers to the second article from the top. Then you can always scroll back up and check your answers.
If you like these PM Puzzlers and think that other people where you work might like ‘em, pass along the link. I believe that these techniques are important and valuable, and from the few correct answers, I have to believe that most people don’t know how to do these calculations. Which is okay – none of us can know something that we’ve never learned!
Fraternally in project management,
Steve the Bajan