Earlier today I set you these puzzles about straws. Here they are again with solutions.
1. Lift-off
Here are three straws. Two are connected to make a upside down V. In the image below, I have leaned the V against the other straw.
Using a fourth straw, can you find a way to lift all the straws off the table? You are allowed to hold the fourth straw, but only the fourth straw is allowed to touch any of the other straws.
Solution: Place the fourth straw between the V and the other straw. Lean towards the V, catch the other straw, and raise them all. Easier to show:
2. Straw poles
Lay out three glasses as below, where the distance between the rims of each glass is the length of a straw.
Using only the three straws, can you find a way to balance a fourth glass on the straws between the three glasses? The straws are not allowed to touch the table, and you cannot move the positions of the glasses. The fourth glass must be equidistant from each of the other glasses.
Solution
3. Three square
Twelve straws are organised in a naughts and crosses pattern as below.
Move straws one by one to create three squares. Each of these squares must consist of four straws, and there must be no extraneous straws left that are not part of one of these squares. There’s a (fairly) obvious way to do it in four moves. But can you do it in three?
Solution
The insight here is to realize that the centre square is not one of the final squares.
The “(fairly) obvious” solution I referred to is to keep the four centre straws in place, and, for example, to move the two top left straws to complete the right top square, and the two bottom left straws to complete the bottom right square. You get a solution which is a mirror image of the above 3-straw solution.
I hope you enjoyed today’s puzzles. I’ll be back in two weeks.
Credits: 1. Jon Hootman. 2. Adapted from Edward de Bono. 3. Scam Nation.
I’ve been setting a puzzle here on alternate Mondays since 2015. I’m always on the look-out for great puzzles. If you would like to suggest one, email me.
