Riddle: A frog fall from a well that is 30 yards deep. Every day he jump 3 yards. Everytime he jump up 3 yards he will fall back 1.5 yards. He only jump once day. How many days he take to jump all the way to the top of the well?
Answer: It is 30 yard! The frog will be already dead!
Source: https://riddles.com/4509