Volume of coin = \(\pi r^2h\) \(=\frac{22}{7}\times0.75\times0.75\times0.2\)
Volume of cylinder = \(\pi r^2h\) \(\,=\frac{22}{7}\times0.75\times0.75\times0.2\)
Therefore,
Total number of coins = \(\frac{Volume\,of\,cylinder}{Volume\,of\,coin}\)
= 450 coins
Thus, 450 coins must be melted to form the required cylinder