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FIRST THE BOYS CROSS THE RIVER. ONE STAYS ASHORE WHILE THE OTHER BRINGS THE BOAT TO THE SOLDIERS AND GETS OUT. A SOLDIER GETS IN THE BOAT AND CROSSES. THE BOY WHO HAS STAYED THERE BRINGS THE BOAT BACK TO THE SOLDIERS, THEN TAKES THE OTHER BOY TO THE OTHER SHORE. AGAIN A BOY BRINGS THE BOAT BACK, GETS OUT, A SECOND SOLDIER CROSSES OVER. THIS PROCESS IS REPEATED UNTIL ALL THE SOLDIERS HAVE CROSSED LET'S SAY THAT THE FARMER IS TRANSPORTING THE WOLF, THE SHEEP AND THE CABBAGE FROM POINT A TO POINT B. FARMER TRANSPORTS THE SHEEP FROM A TO B. FARMER GOES BACK TO A. FARMER TRANSPORTS THE CABBAGE FROM A TO B. FARMER TRANSPORTS THE SHEEP BACK FROM B TO A. FARMER TRANSPORTS THE WOLF FROM A TO B. FARMER GOES BACK TO A. FARMER TRANSPORTS THE SHEEP FROM A TO B LET M = MISSIONARY AND C = CANNIBAL. THIS IS HOW THEY CROSS THE RIVER: M,C → ← M C,C → ← C M,M → ← M,C M,M → NOW, THERE ARE 3 MISSIONARIES AND 1 CANNIBAL ON THE OTHER SIDE OF THE RIVER. THIS CANNIBAL CAN FETCH THE OTHER 2 CANNIBALS ONE BY ONE THE TRAIN IS MOVING AT 40 MILES PER HOUR. IMAGINE THAT A FRIEND IS WALKING WITH YOU. WHEN THE TRAIN WHISTLE BLOWS, YOU HEAD AWAY FROM THE TRAIN, HE HEADS TOWARD IT. WHEN HE REACHES SAFETY, YOU WILL BE 6/8 (OR 3/4)OF THE WAY ACROSS THE BRIDGE, AND THE TRAIN WILL HAVE JUST REACHED THE BRIDGE. FOR THE TRAIN TO CROSS 4/4 OF THE BRIDGE IN THE TIME YOU CROSS THE REMAINING 1/4, THE TRAIN MUST BE MOVING FOUR TIMES YOUR SPEED