Earlier today I set you this puzzle:
You are in a big city where all the streets go in one of two perpendicular directions. You take your car from its parking place and drive on a tour of the city such that you do not pass through the same intersection twice and return back to where you started. If you made 100 left turns, how many right turns did you make?
Solution
96 or 104 right turns.
The path driven by the car does not cross itself. So, when considering the direction of the car, every right turn cancels out a left turn. The net change in direction of the car is 360 degrees (which is 4 left turns, or 4 right turns). So either this was done by four extra left turns (in which case there were 96 right turns) or there were four extra right turns (in which case there were 104 right turns.)
The question made it appear that there was only one answer. Gold stars to those who got both of them.
I hope you enjoyed the puzzle, I’ll be back in two weeks.
I set a puzzle here every two weeks on a Monday. I’m always on the look-out for great puzzles. If you would like to suggest one, email me.
