here are solutions to problems in the reading on problem solving. Of course, you tried to solve them yourself before looking here, right?

The Missionary-Cannibal problem

You could apply the solution to the Tower of Hanoi noted in the main chapter, but here’s a video describing the solution (here to the “Lions and Wildebeest” problem, but it’s the same problem, really):

The Sudoku puzzle and the connect-the-dots puzzle:

The left image shows the solution to the 4x4 sudoku grid: Half of the numbers were supplied to start the puzzle and are colored blue, and half have been filled in as the puzzle’s solution and are colored red. The numbers in each row of the grid, left to right, are as follows. Row 1: blue 3, red 1, red 4, blue 2. Row 2: red 2, blue 4, blue 1, red 3. Row 3: red 1, blue 3, blue 2, red 4. Row 4: blue 4, red 2, red 3, blue 1. The right image shows the solution to the puzzle consisting of 9 dots arranged in 3 rows of 3 inside of a square, where you are supposed to cross all dots with no more than four straight lines without lifting the pencil. The solution is shown by a red line with arrows indicating the direction of movement. In order to solve the puzzle, the lines must extend beyond the borders of the box. The four connecting lines are drawn as follows. Line 1 begins at the top left dot, proceeds through the middle and right dots of the top row, and extends to the right beyond the border of the square. Line 2 extends from the end of line 1, through the right dot of the horizontally centered row, through the middle dot of the bottom row, and beyond the square’s border ending in the space beneath the left dot of the bottom row. Line 3 extends from the end of line 2 upwards through the left dots of the bottom, middle, and top rows. Line 4 extends from the end of line 3 through the middle dot in the middle row and ends at the right dot of the bottom.
For (b): the rules never said your lines had to stay inside the box!

Sam Lloyd’s “Puzzling Scales” figure:

You would need nine marbles to balance the scales.

(want to go back to the main section on problem solving?)