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?

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Aicharya · Accepted Answer

Effective gain per jump (jump up 30 cm then slide 15 cm) $= 15$ cm, except the final jump where the frog comes out and does not slide. The well is 450 cm deep. Before the last jump, the frog needs to be within one jump (30 cm) of the top, i.e. at height $450 - 30 = 420$ cm. To reach 420 cm at 15 cm net per jump takes $420 / 15 = 28$ jumps. The 29th jump of 30 cm takes the frog from 420 cm to 450 cm, out of the well. Hence 29 jumps.

A frog tries to come out of a dried well 4.5 m deep with slippery walls. Every time the frog jumps 30 cm,…

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