Question

A water tank 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.
(i) He jumps 3 steps down and then jumps back 2 steps up. In how many jumps will he reach the water level?
(ii) After drinking water, he wants to go back. For this, he jumps 4 steps up and then jumps back 2 steps down in every move. In how many jumps will he reach back the top step?
(iii) If the number of steps moved down is represented by negative integers and the number of steps moved up by positive integers, represent his moves in part (i) and (ii)
by completing the following; (a) – 3 + 2 – ... = – 8 (b) 4 – 2 + ... = 8. In (a) the sum (– 8) represents going down by eight steps. So, what will the sum 8 in (b) represent?
NCERT Class 7th Mathematics Chapter 1 Integers

Answer 1

1) monkey is on the 1st step, water level is on the 9th step.
1st jump = 1 + 3 - 2 = 2
2nd jump = 2 + 3 - 2 = 3
3rd jump = 3 + 3 - 2 = 4
4th jump = 4 + 3 - 2 = 5
5th jump = 5 + 3 - 2 = 6
6th jump = 6 + 3 - 2 = 7
7th jump = 7 + 3 - 2 = 8
8th jump = 8 + 3 - 2 = 9   

2) 1st jump = 9 - 4 + 2 = 7
2nd jump = 7 - 4 + 2 = 5
3rd jump = 5 - 4 + 2 = 3
4th jump = 3 - 4 + 2 = 1

Answer 2

Answer:

Refer to the attachment for answers.