Another example to trouble your system 1, a.k.a. intuitive thinking and a version of the mileage paradox. It seems even Einstein found this riddle interesting!
I have to cover a distance of 2 kilometres. I did the first kilometre at 15 km/h (km. per hour). What speed should I maintain in the next one kilometre to cover the total distance at an average speed of 30 km/h?
System 2 thinking
You may require a pen a paper to solve this puzzle. Take the first part: how much time does it take to cover one km at 15 km/h? The answer is 60/15 = 4 min. The second part, time to cover two km at 30 km/h: 60 mins for 30 km, 2 mins for 1 km or 4 mins for 2 km. But you already consumed 4 mins in the first one km!
So I can’t achieve the target; was it obvious the first time you heard the problem?
