Measure the depth of the dry well with a rope. Single strand outside the well10m, double strand 2m. How deep is this dry well?

Solution: When measuring the dry well depth with one rope, the surplus is 10m outside the single-strand logging, and the rope length = well depth+10.

Two strands are more than 2m: rope length = 2 times well depth +2 * 2 = 2 well depth +4,

So: well depth+10 = 2 well depth +4, resulting in well depth = 6m.

A: A little.