Assume the number of cones made be n

It is given that,

Radius of metallic sphere $=5.6cm$

Radius of the cone $=2.8cm$

Height of the cone $=3.2cm$

As we know that,

Formula for volume of a sphere $=4/3\pi \times {{r}^{3}}$

Then, ${{V}_{1}}=4/3\pi \times {{5.6}^{3}}$

Volume of cone $=1/3\pi \times {{r}^{2}}\times h$

${{V}_{2}}=1/3\pi \times {{2.8}^{2}}\times 3.2$

Thus, the number of cones (n) $=$ Volume of the sphere/ Volume of the cone

$n=4/3\pi \times {{5.6}^{3}}/\left( 1/3\pi \times {{2.8}^{2}}\times 3.2 \right)$

$n=\left( 4\times {{5.6}^{3}} \right)/\left( {{2.8}^{2}}\times 3.2 \right)$

$n=28$

Hence, $28$ such cones can be formed.