a)
V = 4/3·pi·3^3 + pi·3^2·5 = 81·pi = 254.5 mm³
b)
O = 4·pi·3^2 + 2·pi·3·5 = 66·pi = 207.3 mm²
c)
2·pi·3·5 = 30·pi
p = 30·pi / (66·pi) = 5/11 = 0.4545 = 45.45%
d)
V = pi·r^2·h --> r = √(V / (pi·h)) = √(81·pi / (pi·4)) = 4.5 mm
d = 2·r = 2·4.5 = 9 mm