6. The Jackals and the Coyotes
Three Jackals and three coyotes are on a trek across the Mokalani Plateau when they come to a river filled with carnivorous fish. There is a rowboat in sight, and the party decides to use it. However, the boat is too small for any more than two of the group at a time. So they must traverse the river in successive crossings. There is one hitch, though. The jackals must not outnumber the coyotes at any time, in any place. If it happens, for example, that there are two jackals on the western bank, and only one coyote (or 2 jackals in the boat when it arrives at the western back where there is a lone coyote), then this problem is reduced to simple subtraction and gluttony (the 2 jackals will jump out of the boat and eat the coyote on the bank). It's okay to have an equal number of each, and it is also okay to have more coyotes than jackals in a given place. Neither situation poses a danger to the coyotes, and the coyotes do not pose a threat to the jackals. So, the trick here is to use the one small rowboat, a lot of sweat, and a little brainpower to assure the coyotes' survival while both groups cross the river. Show how it can be done (Hint: try using small pieces of paper as manipulatives to move the J's and C's back a forth across the river).