(i) curved surface area of cone = 308 cm² and slant height l = 14 cm.
Let, the radius of base of cone = r cm
Curved surface area of cone = πrl
⇒ 308 = 22/7 × r × 14
⇒ 308 = 44r
⇒ r = 308/44 = 7 cm
Hence, the radius of base of cone is 7 cm.

(ii) Total surface area of cone = πr(r + l)
= 22/7 × 7 × (7 + 14)
= 22 × 21
= 462 cm²
Hence, the total surface area of cone is 462 cm².

Radius of cone r = 6 m and height h = 8 m
let, the slant height = l m
We know that, l² = r² + h²
⇒ l² = 6² + 8² = 36 + 64 = 100
⇒ l = √100 = 10 m
Area of tarpaulin to make the tent = πrl
= 3.14 × 6 × 10 = 188.40 m²
Let, the length of 3 m wide tarpaulin = L
Therefore, the area of tarpaulin required = 3 × L
According to question,
3 × L = 188.40
⇒ L = 188.40/3 = 62.80 m
Extra tarpaulin for stitching margins and wastage = 20 cm = 0.20 m
Therefore, the total lenght of tarpaulin = 62.80 + 0.20 = 63 m
Hence, the length of 3 m wide tarpaulin is 63 m to make the tent.