Curved surface area of cylindrical reservoir 12 m deep . . .

Question : Curved surface area of cylindrical reservoir 12 m deep is plastered from inside with concrete mixture at the rate of Rs 15 per m². If the total payment made is of Rs 5652, then find the capacity of this reservoir in litres. Use π=3.14.

Doubt by Saksham

Solution : 

h = 12 m

Rate = Rs 15 Per m²

Cost = Rs 5652

Curved surface Area of Cylindrical reservoir
= Cost /Rate
= 5652/15 m²
2πrh= 5652/15
2(3.14)×r×12 = 5652/15
6.28×r×12 = 5652/15
r = (5652)/(6.28×12×15)

r = 5 m

Volume of cylindrical reservoir
=πr²h
= 3.14×(5)²×12

= 942 m³

=942×1000 l
= 942000 l