How to implement a fourth order Butterworth LP filter at 1kHz if sampling frequency is 8 kHz? | Embedded Interview Questions

A fourth order Butterworth filter can be made as cascade of two second order LP filters with zeta of 0.924 and 0.383. One can use a bilinear transformation approach for realizing second order LP filters. Using this technique described well in many texts, one can make two second order LP filters and cascade them.