Question

A building is in the form of a hollow hemisphere of outer radius 100 m and thickness of wall
is 1 m. If cost of painting 1 sq.m. ia Rs. 5 then total cost of painting both the outer and inner
walls of the building is
​

Answer 1

Answer:given,

internal diameter=21cm

internal radius=21/2=10.5cm

external diameter=25.2cm

external radius=25.2/2 =12.6cm

surface area of internal bowl=2πr²

=2(22/7)(10.5²)

=2×22×10.5×10.5/7

=693cm²

surface area of external bowl=2πR²

=2(22/7)(12.6²)

=2×22×12.6×12.6/7

=997.9cm²

surface area of ring=π(R²-r²)

=22/7(12.6²-10.5²)

=22/7(48.51)

=22×48.51/7

=152.46cm²

cost of internal bowl=693×0.1=69.3

cost of external bowl=997.9×0.1=99.79

cost of ring=152.46×0.1=15.246

cost of bowl=69.3+99.7+15.2=184.2

MAYBE IT IS CORRECT

Explanation: hope this helps you plz mark me as the brainliest