Book Solutions

These are the solutions to the exercises on pages 19-20 :

Out of the box

With 4 lines there are different solutions possible to this problem. They all require that you draw outside the boundaries of the 9 dots. Here are two examples. It is also possible with 3 lines only, although that would require a very large page… think about it.

Solution 2Solution



Live with your limitations.

The solution is as follows : switch on the first switch and leave it on for a few minutes. Next do the following quickly : Switch off the first switch, switch on the second one. Go into the room and check :

– if the lamp is on, then the right answer is switch nr 2

– if the lamp is off, check if it is hot or not

– if it is hot, then the right answer is switch nr 1

– if it is still cold, then the right answer is switch nr 3

I’ve learned this from Joey Stoole, who at 9 years old solved the problem within a few minutes.