Water level in a well was 20m below ground level. During rainy season, rainwater collected in different water tanks was drained into the well and the water level rise 5 m above the previous level. The wall of the well is 1m 20cm high and a pulley affixed at a height of 80 cm. Raghu wants to draw water from the well. Find the minimum length of the rope that he can use.

17 m

Step-by-step explanation:

As shown in the figure,   is the ground level, is the old level of water which was at 20 m below ground level, 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 in the figure.

So,

Hence, Raghu must use a rope having the minimum length 17 m to draw water from the well.