Base circumference of cylinder (c) = 8 cm

So, the radius

Length of the cylinder (h) = 21 cm

(i) If distance covered in one revolution is 8 cm, then distance covered in 9 revolutions = 9 x 8 = 72 cm or distance covered in 1 second = 72 cm.

Thus, distance covered in 4½ seconds

(ii) Curved surface area

So, the area covered in one revolution = 168 cm^{2}

Then,

The area covered in 9 revolutions

Which is also the area covered in 1 second = 1512 cm^{2}

Therefore, the area covered in 4½ seconds