Question

9. The inner diameter of a circular well is 3.5 m. The depth of the well is 15 m. Find the cost of plastering
the inner curved surface at the rate of 25
per
m2
​

Answer 1

Answer:

hey friend your answer is

Step-by-step explanation:

Inner diameter = 3.5m

Inner radius = 3.5/2 = 1.75m

Height / Depth = 15m

CSA = 2πrh

2 × 22/7 × 1.75 × 15

= 44 × 0.25 × 15 [ 1.75 ÷ 7 = 0.25]

= 165 cm²

Rate = 25 per m²

Cost = Area × Rate

Cost = 165 × 25

Cost = ₹ 4125 .

hence the answer is ₹ 4125.

Answer 2

CSA = dπh

CSA = 3.5*(22/7)*15

CSA = 165cm²

Cost of plastering = 165*25 = 4125 Rs