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NCERT Solutions Class 9 Mathematics Solutions for Surface Areas and Volumes - Exercise 13.8 in Chapter 13 - Surface Areas and Volumes

Question 8 Surface Areas and Volumes - Exercise 13.8

A dome of a building is in the form of a hemi sphere. From inside, it was white-washed at the

cost of Rs. 4989.60. If the cost of white-washing is Rs 20 per square meter, find the

(i) inside surface area of the dome, (ii) volume of the air inside the dome

(Assume π = 22/7)

Answer:

(i)Cost of white-washing the dome from inside = Rs 4989.60

Radius is 6.3 m

The volume of air inside the dome =Volume of hemispherical dome

Using the formula, the volume of the hemisphere = 2 / 3 \pi \mathrm{r}^{3}

= 2/3 x 22/7 x 6.3 x 6.3 x 6.3

= 523.908

= 523.9 (approx.)

Answer: Volume of air inside the dome is 523.9 \mathrm{m}^{3}

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