Use ruler and a pair of compasses only in this question :

(i) Draw a circle on AB = 6.4 cm as diameter.

(ii) Construct another circle of radius 2.5 cm to touch the circle in (i) above and the diameter AB produced.

The internal and external diameters of a hollow hemispherical vessel are 14 cm and 21 cm respectively. The cost of silver plating of 1 cm² of its surface is ₹ 32. Find the total cost of silver plating the vessel all over.