Earlier today I set you a classic 19th century puzzle
The T-puzzle
Rearrange the four pieces to make a T. The pieces cannot overlap and must fit in to the given template. Flipping pieces is allowed.
For an interactive version click here. For a printable version click here
Scroll below for the answer. (I didnt want to put the solution high on the page, just in case you haven’t seen it before and want to try it out first on this interactive app.) You can move the pieces with your thumb/mouse and rotate them by clicking, or pressing the buttons. The third button is for flips.
The T-puzzle is simple, a primary school standard, and yet challenging to many. According to this research paper, out of five undergraduates given the puzzle the fastest took 2mins 20, the second about 9mins and the other three more than 15mins (and required a hint.)
The interactive app, created by reader Phoebe Fletcher, has a timer and I was interested to see how you all got on.
The stats
Number who gave it a go: 24,256
Number who solved it: 9,650 (39.8 per cent)
Fastest time. 6s
Slowest time: 52m 46s
Median time: 1m 57s
Mean time: 3m 6s
The 6 second response was I’m sure by someone who had seen the puzzle before, although I am extremely impressed by their nimble fingers. The 52 minute response might have been someone who fell asleep.
The median, at just under two minutes, is about the same as the fastest undergraduate in the academic paper, which makes me think that the paper is more or less correct. Of those who can get it, it comes quite quickly – but for many people it really is quite tough.
And now for the solution. The key insight is that the pentagonal piece must be diagonal. People who fail to solve it assume that it must be placed vertically or horizontal.
I hope you enjoyed the puzzle and I’ll be back in two weeks.
Thanks to Phoebe Fletcher for designing the interactive puzzle.
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.
