Answer:
17 m
Step-by-step explanation:
As shown in the figure, [tex]A_0-B_0[/tex] is the ground level, [tex]A_1-B_1[/tex] is the old level of water which was at 20 m below ground level, [tex]A_2-B_2[/tex] is the new level of water which is 5m above of old level. The height of wall of the well, 1.20 m, and the the pelly at 80 cm =0.80 m, has been shown too.
The minimum length of the rope is equal to the distance between the pully and the new water level, indicated by the length [tex]L_0[/tex] in the figure.
So, [tex]L_0= 20-5+1.20+0.80= 17m[/tex]
Hence, Raghu must use a rope having the minimum length 17 m to draw water from the well.