# How Many Cubic Meters of Earth Must Be Dug Out to Make a Well 28 M Deep and 2.8 M in Diameter ? Also , Find the Cost of Plastering Its Inner Surface Ata Rs 4.50 per Sq.Meter. - Mathematics

Sum

How many cubic meters of earth must be dug out to make a well 28 m deep and 2.8 m in diameter ? Also , find the cost of plastering its inner surface ata Rs 4.50 per sq.meter.

#### Solution

"Radius of the well"=2.8/2=1.4 m

"Depth of the well"=28m

"Therefore, volume of earth dug out "= pir^h

=22/7xx1.4xx1.4xx28

=17248/100

=172.48 m^2

"Area of curved surface"=2pirh

=2xx22/7xx1.4xx28

=246.40 m^

Cost of plastering the rate of Rs 4.50 per sq m

= Rs. 246.40xx450

= Rs 1108.80

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#### APPEARS IN

Selina Concise Maths Class 10 ICSE
Chapter 20 Cylinder, Cone and Sphere
Exercise 20 (A) | Q 4 | Page 297