Five men and five boys have to cross the Mississippi River to attend a birthday party.  They have only one row boat with them.  Because of the small size of the row boat, the boat can not carry more than one man, or more than two boys.  Thus, a man riding with a boy would not be possible.  What would be the least number of boat trips that would take everyone to the other shore?

Trip 1.  2 Boys row across.

Trip 2.  1 Boy comes back.

Trip 3.  1 Man rows across.

Trip 4.  1 Boy come back.

Trips 5 to 8.  Repeat trips 1 to 4.

Trips 9 to 12.   Repeat trips 1 to 4.

Trips 13 to 16.   Repeat trips 1 to 4.

Trips 17 to 20.   Repeat trips 1 to 4.

Trip 21.  2 Boys row across.

Trip 22.  1 Boy comes backs.

Trips 23 to 24.  Repeat trips 21 and 22.

Trips 25 to 26.  Repeat trips 21 and 22.

Trips 27.  2 Boys row acriss.

All men and boys are now across Mississippi River enjoying the party!