GeekDad Puzzle of the Week: Bolder Boulder

Here's a proud dad moment: my six-year-old, Leif, just walked or ran every step of the 10k Bolder Boulder race. Sure we had to hustle a couple hundred yards to get ahead of the cutoff van, and ended up finishing just a couple steps ahead of the elite female winner, who started about an hour and forty minutes later than we did. But running a race of 50k people to finish in the packed stadium of CU Boulder was awesome.
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The Bolder Boulder, because my phone was out of battery, courtesy of Flickr/scubadive67 cc license.

Here's a proud dad moment: my six-year-old, Leif, just walked or ran every step of the 10k Bolder Boulder race. Sure we had to hustle a couple hundred yards to get ahead of the cutoff van, and ended up finishing just a couple steps ahead of the elite female winner, who started about an hour and forty minutes later than we did. But running a race of 50k people to finish in the packed stadium of CU Boulder was awesome.

I blame the slow time on, as Admiral James Stockdale would say, Griiiiiidlock! With 50k people, we started in waves, each two minutes later than the next. Being perhaps a bit less confident of being lightning fast, we started at the very back. Imagine waves started at 7:00am and that we started last at 9:00am. Every wave consisted of 500 runners. 1/20 ran 6-minute miles, 1/20 ran 7-minute miles, 1/20 ran 8-minute miles, etc. until 1/20 ran 25-minute miles. Image Leif and I (and Kristi with our four-year-old mostly on her shoulders) "ran" 18-minute miles.

How many people did we pass?

Submit your answer to Geekdad Puzzle Central by Friday for your chance at a $50 ThinkGeek gift certificate!