You're in a war. You spot three enemy tanks, with the numbers 5, 10 and 20 on them. The number signify the serial number of the tank. What's the expected number of tanks the enemy has? The enemy isn't smart enough for trickery, tank 20 is the 20th tank they manufactured etc.


I have no idea how to even start solving this. My hunch would be it's less than 100 since we saw three low numbers. Surely if they had a million tanks we'd see like 134924, 300349 and 572845