Question

A dome of a building is in the form of hemisphere. From inside, it was white washed at the cost of Rs 498.96. If the cost of white washing is Rs 2.00 per square metre, find the volume of air inside the dome
plz telll fast as fast a possible

Answer 1

the the inner surface area of the dome is nothing but the total cost of whitewashing divided by the rate per metre. hence has the inner surface area=498.96/2=249.48m². now, inner surface area=2πr². therefore 2πr²=249.48 , which gives r=6.3 m.so, volume=2/3*πr³ =523.908 m³

Answer 2

Answer:

ANSWER

(i) We know that

Area whitewashed × Cost of white wash = Total cost

Area whitewashed ×2=498.96

Area whitewashed =2498.96

Area whitewashed =249.48 m2

Now,

Area of whitewashed is curved surface area of hemisphere (as only walls are whitewashed, not floor)

Therefore,

Inner surface area of dome =249.48 m2

(ii) Volume of air inside dome = Volume of hemisphere

                                                  =32πr3

Let the radius of dome be 'r' m

Surface area of dome =249.48 m2

                              2πr2=249.48

              2×722×r2=249.48

                                r2=39.69

                                r=39.69

                                r=6.3 m

Volume of air inside the dome = Volume of hemisphere

                                                    =32πr3

                                                    =32×722×6.33

                                                    =523.9 m3