$($ii$)$ Determine the order $\backslash ($ n $\backslash )$ of the prototype lowpass filter $($given the stopband attenuation and ripple specifications$)$

$($iii$)$ Determine the $\backslash ($ z $\backslash )-$domain transfer function, difference equation and hence, the coefficients of the IIR filter using the BZT $($Bilinear z$-$Transform$)$ method.

$($iv$)$ Draw a Direct$-$Form II block realisation of the filter using the derived $\backslash ($ b$\_\{$j$\}\backslash )$ and $\backslash ($ a$\_\{$i$\}\backslash )$ coefficient weights.