Solution:

Given radius of the cylinder, r = 3.5 cm

Height of the cylinder, h = 7.5 cm

Total surface area = 2r(r+h)

Curved surface area = 2rh

Ratio of Total surface area to curved surface area = 2r(r+h)/ 2rh

= (r+h)/h

= (3.5+7.5)/7.5

= 11/7.5

= 22/15

Hence the required ratio is 22:15.