Kenken classroom: Puzzles that make math fun

This brain teaser is a twist on the crossing-the-river problem from Primarily Math. To get "NCTM KenKen," a FREE, all-new, totally fun, awesome app now available for any iPhone or iPad, click here:

River Run

There are four people who want to cross a river. The only way to get across is by a boat that can fit a maximum of two people at a time. They begin on the same side of the river and have altogether 17 minutes to get to the other side. Each person rows at a different speed, and if two people are in the boat together they have to row at the rate of the slower person. How do they all get across?

Abby: 1 minute to cross
Bernard: 2 minutes to cross
Carly: 5 minutes to cross
Daniel: 10 minutes to cross

More puzzles can be found at:

Lindsay - you may need to put the answer on the last page of the newsletter. I don't know if the answer key will still be there for this newsletter.

River Run Answer
They go across in this order:
Abby and Bernard cross together --------------- 2 minutes
Abby comes back (Bernard stays)--------------- 1 minute
Carly and Daniel cross together ----------------- 10 minutes
Bernard comes back (Carly and Daniel stay)--- 2 minutes
Abby and Bernard cross together ---------------- 2 minutes