The inner diameter of a circular well is 3.5 m. It is 10 m deep. Find:

Question:

The inner diameter of a circular well is 3.5 m. It is 10 m deep. Find:

(a) Inner curved surface area

(b) The cost of plastering this curved surface at the rate of Rs 40 per $m^{2}$.

Solution:

The inner diameter of the well = 3.5 m

Inner radius = 3.52 = 1.75 m

Height of the well = 10 m

(a) Inner curved surface area

= 2πrh

= 2 * 3.14 * 1.75 * 10

$=110 m^{2}$

(b) Cost of painting $1 \mathrm{~m}^{2}$ area of the well

= Rs 40

Cost of painting $110 \mathrm{~m}^{2}$ area of the well

= Rs (50*110) = Rs 4400