A frog tries to come out of a dried well 4.5 m deep with slippery walls

A frog tries to come out of a dried well 4.5 m deep with slippery walls. Every time the frog jumps 30 cm, slides down 15 cm. What is the number of jumps required for the frog to come out of the well?

1. 28
2. 29
3. 30
4. 31

• Answer: The correct option is B
• Explanation:

  Total length of the wall = 4.5 m = 450 cm

  Total length covered by frog in one jump = 30 - 15 = 15 cm

  Number of jumps required by frog to cover 420 cm = 420/15 = 28 jumps

  So, in the 29th jump, the frog will reach at the top of the wall and will not slide down.

• Exam Year: 2020