Resources for students & teachers

PROBLEM 2.  Second from right end

                   Doors No. of No. of
Settings open doors open right door
 1..................5.6.7.8....................4.......
...........7
 2..................2.3.4.5.6..................5.......
...........5
 3..................1.2.3.4.5.6.7.8.9..........9.......
...........8
 4..................5.6.7......................3.......
...........6
 5..................1.2.3.4....................4.......
...........3
 6..................4.5.6......................3.......
...........5
 7..................2.3.4.5....................4.......
...........4
 8..................1.2.3......................3.......
...........2
 9..................1.2.3.4.5.6.7..............7.......
...........6
10..................2.3.4.5.6.7.8.9............8............
......8

PROBLEM 3.  Alternate left and right ends

                   Doors No. of No. of
Settings open doors open right door
 1..................5.6........................2.......
...........5
 2..................5.6........................2.......
...........6
 3..................4.5.6.7.8.9................6.......
...........4
 4..................4.5.6.7.8.9................6.......
...........9
 5..................1.2.3.4.5..................5.......
...........1
 6..................1.2.3.4.5..................5.......
...........5
 7..................2.3.4.5.6.7................6.......
...........2
 8..................2.3.4.5.6.7................6.......
...........7
 9..................3.4.5.6.7.8................6.......
...........3
10..................3.4.5.6.7.8................6............
......8

PROBLEM 4.  Middle

                   Doors No. of No. of
Settings open doors open right door
 1..................4.5.6.7.8..................5.......
...........6
 2..................1.2.3......................3.......
...........2
 3..................1.2.3.4.5.6.7.8.9..........9.......
...........5
 4..................2.3.4.5.6..................5.......
...........4
 5..................6.7.8......................3.......
...........7
 6..................3.4.5.6.7.8.9..............7.......
...........6
 7..................7.8.9......................3.......
...........8
 8..................1.2.3.4.5.6.7..............7.......
...........4
 9..................2.3.4......................3.......
...........3
10..................3.4.5.6.7..................5............
......5