Question

a water tank 21m deep is of radius 2m.Find the cost of cementing the inner curved surface at the rate of rupees 5 per square metre

Answer 1

height of the tank=21m
radius of the tank=2m
curved surface area =
$2\pi \: rh$
$2 \times \frac{22}{7} \times 2 \times 21$
$\frac{44}{1} \times 2 \times 3$
$44 \times 6$
$264 {m}^{2}$
cost of cementing 264m square =264× 5
1320 rupees