Solution:

Given radius of the metal cylinder, r = 14 cm

Height of the metal cylinder, h = 21 cm

Radius of the sphere, R = 3.5 cm

Volume of the metal cylinder = r²h

= (22/7)×14²×21

= 22×2×14×21

= 12936 cm³

Volume of sphere = (4/3)R³

= (4/3)×(22/7)×3.5³

= 11×49/3

= 539/3 cm³

Number of spheres that can be made = Volume of the metal cylinder/ Volume of sphere

= 12936 ÷539/3

= 12936 ×3/539

= 72

Hence the number of spheres that can be made is 72.