Question

9, Estimate the cost of painting the inner wall
of a well, if the depth of the well is 14 ft
and the diameter is 8 ft. The cost of painting
2.5 sq. ft is 20.​

Answer 1

here , depth = 14 ft

diameter = 8 feet

so , radius = 4 ft

We will paint it on its C.S.A.

C.S.A. of cylinderical well

= 2πrh

= 2×(22/7)× 4 × 14

= 352 ft²

so ,

cost = rate per unit area × area

= (20/2.5)×352

= 8×352

= 2816

so , cost of painting will be 2816 rupees

Answer 2

Answer:

Given that :

height equal to 14 feet

radius equals to 4feet

rate of painting2.5 feet square equals to 20 rupees

curved surface area of cylinder of inner walls Of well=2πrh

= 2×22/7×4×14

=352feet square

cost of painting 352 feet square =20\2.5×352

=8×352

=2816 rs.