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.