Pirate Jim has 8 boxes filled with gun powder that weigh 1, 2, 3, 4, 5, 6, 7, and
8 pounds, and the weight of each box is printed on its top. Pirate Bob then hid a
1-pound gold bar in one of the boxes. Pirate Jim cannot open any of the boxes, but
he has a balance scale that he can use to make exactly two weighings. Can he find
the gold bar?