# Find the cost of sinking a tubewell 280 m deep, having diameter 3 m at the rate of Rs 3.60 per cubic metre. Find also the cost of cementing its inner curved surface at Rs 2.50 per square metre. - Mathematics

Sum

Find the cost of sinking a tubewell 280 m deep, having diameter 3 m at the rate of Rs 3.60 per cubic metre. Find also the cost of cementing its inner curved surface at Rs 2.50 per square metre.

#### Solution

Given data is as follows:

Height of the tube well = 280 m

Diameter = 3 m

Rate of sinking the tube well = Rs.3.60/m3

Rate of cementing = Rs.2.50/m2

Given is the diameter of the tube well which is 3 meters. Therefore,

r = 3/2m

Volume of the tube well = pir^2h

= 22/7 xx 3/2 xx3/2xx280

= 1980 m2

Cost of sinking the tube well = Volume of the tube well × Rate for sinking the tube well

=1980 × 3.60

= Rs. 7128

Curved surface area = 2pirh

= 2 xx 22/7 xx 3/2 xx 280

=2640  m2

Cost of cementing = "Curved Surface Area " xx " Rate of cementing"

= 2640 × 2.50

= Rs.6600

Therefore, the total cost of sinking the tube well is Rs.7128 and the total cost of cementing its inner surface is Rs.6600.

Concept: Surface Area of Cylinder
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#### APPEARS IN

RD Sharma Mathematics for Class 9
Chapter 19 Surface Areas and Volume of a Circular Cylinder
Exercise 19.2 | Q 24 | Page 22

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