School-Safe Puzzle Games

The Good Pedestrian

twin-bicyle-math-puzzle1

Three students had a twin bicycle (similar to above, but only 2 seats) and wished to go just 40 miles. The bike could complete the journey with 2 riders in one hour, but could not carry the three simultaneously.

Well, one who was a good pedestrian could walk at the rate of one mile in 10 minutes. another could walk the same in 15 minutes, and the other in twenty.

What would be the best possible time in which all three could get to the end of their journey?

* the bike can backtrack

* the bike travels at the same speed regardless of which pair of students is riding it

Not sure how many will be able to get this hard math puzzle; if you can figure it out out, feel free to enter your answer below. Will unmask in several days…