Question

A dome of a building is in the form of a hemisphere. From inside, it was whitewashed at the cost of ₹498.96. If the rate of whitewashing is ₹4 per square metre, find the : (i) Inside surface area of the dome (ii) radius of the dome.​

Answer 1

Answer:

(i) Inside surface area of the dome is 124.74 m²

(ii) radius of the dome is 4.45 m

Step-by-step explanation:

Given : Dome inside white washing cost = 498.96 Rs

            the rate of whitewashing is ₹4 per square meter

            Inside surface area = ?

            Radius of Dome = ?

Solution : Inside surface area of dome = White washing cost/ rate

                                                                = 498.96/4

                                                                = 124.74 m²

As given Dome shape is hemisphere,

So Surface area of hemisphere = 2 x π x R²          R - radius of dome

                                       124.74 = 2 x 22/7 x R²

                                             R² = 124.74  x 7/22 x 2

                                                  = 19.85

                                             R = $\sqrt{19.85}$

                                                = 4.45 m