Question

What is the turn ratio of gear wheels of your wrist watch?

Answer 1

Gear ratios are chosen to convert the time counted by the escape wheel into minutes and hours. For a normal watch, 60 second escape wheel a 60:1 ratio is needed to count 60 minutes for one hour. Then to count 12 hours, a 12:1 ratio is needed.

But interesting thing is that no watches uses these gear ratios, they use an array of gears of smaller ratios for high accuracy.
For example, choose a train with a 15:1 followed by a 4:1 to get 60:1.