Question

Curved surface area of a cylindrical reservoir 12m deep is plastered from inside with concrete mixture at the rate of rs 15 per m^2. If the total payment made is of rs.5652, then find the capacity of this reservoir in litres

Answer 1

i ) depth of the reservoir = h = 12 m

Curved surface area of the reservoir = 2×pi×r×h

CSA = 2 × pi × r × 12 m

CSA = 24 × pi × r -------- ( 1 )

ii ) 1 m^2 plastering the reservoir cost Rs 15

Total cost of the plastering = Rs 5652

CSA of the reservoir = 5652 / 15 m^2 ----( 2 )

( 1 ) = ( 2 )

24 × pi × r = 5652 / 15

r = ( 5652 ) / ( 15 × 24 × pi )

r = 15.7 / pi -----( 3 )

iii ) volume of the reservoir = pi × r^2 × h

V = pi × ( 15.7 / pi ) × ( 15.7 / pi ) × 12

V = ( 15.7 × 15.7 × 12 ) / pi

= ( 15.7 × 15.7 × 12 ) / ( 22 / 7 )

V = 20705.16 / 22

V = 941. 14 m^3

= 941 .14 × 1000 li

= 941140 li

Therefore ,

Capacity of the reservoir = 941140 li