An interesting Question

I got this from "Rule Of Four", a international best seller.
A well is 10 feet deep, and a frog is at the bottom of the well.
The frog can climb 3 feet up in the daytime, but slides 2 feet down when it is sleeping.
How long will it take the frog to get out of the well?
There was no correct answer in the book, just suggestions.
1. Never. The frog will give up after 2 days. It is a frog, has to eat and all, not concerned about climbing out of the well.
2. Any answer. Some will assume this question is testing creativity, just something fanciful will suffice.
3. Maths. This may be the most common route poeple will tackle this question. However, let's take it step by step.
The frog travels up 3 feet, but slides 2 feet. Hence:
Distance travelled by Frog = 3 - 2
= 1 feet.
Distance to be travelled = 10 feet.
Hence, Time taken for Frog to travel out of well = 10/1 + 1
= 11 Days.
Mathematically, WRONG.
Why?
Distance travelled in a day by Frog = 1 feet.
However, on start the 8th day, Frog has travelled 7 feet up.
Since he travels up 3 feet in daytime, and slides down only when he sleeps, he will hop happily out of the well on the 8th day.
Interesting isn't it? :)