Given: diameter of sphere = 21 cm

∴ radius of sphere = r_s = (21/2) cm

Diameter of cone = 3.5 cm

∴ radius of cone = r_c = 3.5/2 = 1.75 = (7/4) cm

Height of cone = h = 3 cm

Formula: volume of sphere = (4/3)πr_s³

Volume of cone = (1/3)πr_c²h

Sphere is melted and then cones are made from molten metal therefore the volume remains same

Let ‘n’ be the number of cones made

i.e. volume of n cones = volume of sphere

∴ n × (1/3) × π × r_c² × h = (4/3) × π × r_s³

Therefore number of cones formed = 504