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Water level in a well was 20m below ground level. During rainy season, rain water collected in different water tanks was drained into the well and the water level rises 5 m above the previous level. The wall of the well is 1 m 20 cm high and a pulley is fixed at a height of 80 cm. Raghu wants to draw water from the well. The minimum length of the rope that he can use is
a. 17 m
b. 18 m
c. 96 m
d. 97 m

Solution:

To solve the above given problem let us first note down the given parameters.

Height of the wall of the well = 1m 20 cm

If we convert 1m 20 cm to meters we have = 1m 20 cm = 1.2 m

Height of the fixed pulley = 80 cm
If we convert 80 cm to meters we have = 80 cm = 0.8 m

It is given that initially water was available at a depth of 20 m below ground level.

After rainfall the water level was raised by 5 m.

Now the new depth at which water is available after rainfall = 20 - 5 = 15 m

Therefore using the integer rules we evaluated that the minimum length of the rope required to draw water from the well will be (1.2 + 0.8 + 15) m = 17 m.

✦ Try This: A plane is flying at the height of 300000 m above sea level. At some point, it is exactly above the submarine floating 7000 m below sea level. What is the vertical distance between the plane and submarine?

To calculate the vertical distance between plane and submarine we can use the subtraction of two integers and determine the distance. This results in 300000 -(-7000) = 300000 + 7000 = 307000 m

☛ Also Check: NCERT Solutions for Class 7 Maths Chapter 1

NCERT Exemplar Class 7 Maths Chapter 1 Exercise Problem 11

Water level in a well was 20m below ground level. During rainy season, rain water collected in different water tanks was drained into the well and the water level rises 5 m above the previous level. The wall of the well is 1m 20 cm high and a pulley is fixed at a height of 80 cm. Raghu wants to draw water from the well. The minimum length of the rope that he can use is: 17m, 18m, 96m, 97m

Summary:

Using the integer rules we evaluated that the minimum length of the rope required to draw water from the well will be a sum of 1.2 + 0.8 + 15 which results in 17 m

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