Problem Solving

THREE WEALTHY MEN AND THREE ROBBERS


THREE WEALTHY MEN AND THREE ROBBERS ARE TRAVELING TOGETHER. THEY COME TO A RIVER THAT THEY MUST CROSS. THE ONLY BOAT AVAILABLE CARRIES TWO PEOPLE AT A TIME. THE WEALTHY MEN MUST BE CAREFUL THAT THERE ARE NEVER MORE ROBBERS THAN WEALTHY MEN ON THE SAME SIDE OF THE RIVER OR THEY WILL BE ROBBED. HOW MANY TRIPS WILL IT TAKE FOR THEM ALL TO CROSS SAFELY??? (source unknown)

For the answer (try not to look right away!).