A hemi-spherical bowl has 3.5 cm radius. It is to be painted inside as well as outside. The cost of painting it at the rate of ₹5 per 10 sq.cm will be:

Radius of hemispherical bowl = 3.5 cm

Curved surface area of the hemisphere = $$2\pi r^2$$

= $$2\times\frac{22}{7}\times(3.5)^2$$

= $$\frac{44}{7}\times12.25=77$$ $$cm^2$$

As bowl is to be painted inside and outside, thus total surface to be painted = $$2\times77=154$$ $$cm^2$$

Now, cost of painting $$10$$ $$cm^2$$ = $$Rs.$$ $$5$$

$$\therefore$$ ost of painting $$154$$ $$cm^2$$ = $$\frac{5}{10}\times154=Rs.$$ $$77$$

=> Ans - (A)