Question

A deep well has steps inside it. A monkey is sitting on the topmost step (i.e. the first step). The water level is at the ninth step. To go one step down, the monkey jumps 3 steps down in the first jump and then jumps back 2 steps up in the second jump, how many jumps does it have to make to reach the water level?
(4 marks)

Answer 1

Here, jumping downwards is taken as positive and jumping upwards is taken as negative.
Its given that the monkey is sitting on the first step.

To reach the second step, the monkey will jump twice i.e. (+3) + (-2) = 1

(1 mark)

$\Rightarrow$ To reach the third step, the monkey will again jump twice i.e., (+3) + (-2) = 1

$\Rightarrow$ To reach the fourth step, the monkey will again jump twice i.e., (+3) + (-2) = 1

$\Rightarrow$ To reach the fifth step, the monkey will again jump twice i.e., (+3) + (-2) = 1

$\Rightarrow$ To reach the sixth step, the monkey will again jump twice i.e., (+3) + (-2) = 1

(2 marks)

Now, the monkey has reached sixth step.
It will jump three steps down then, it will reach ninth step.

Number of jumps required to reach the water level = 2 + 2 + 2 + 2 + 2 + 1 = 11.

(1 mark)