Five members of the Varsity Math team are running late for a big
competition and hurrying toward the arena - but they forgot that they would
have to cross the stream that cuts through campus. When they reach the
stream, there's a small boat tied up on their side that they can "borrow" to get
to the other side.
The boat will hold one, two or three of the students, but not more.
Fortunately, two of the team members are also on the crew team, and when
the boat contains only one or both of them, they can make it across the stream
in one minute. Unfortunately, the other three teammates are very
inexperienced with boats, and when any of them is aboard, there is so much
awkwardness and flailing that the crossing will take four minutes, regardless
of whether one of the crew teammates is on board.
The team members adopt the fastest strategy for rowing back and forth
across the stream to get everyone to the other side for the competition. How
many minutes does it take all five team members to get across?