plZ help me in my homework

A signal m1(t) is band-limited to 3.6kHz, and the three other signals, m2(t),m3(t), and m4(t), are band-limited to 1.2kHz each. These signals are sampled at the Nyquist rate and binary coded using 512 levels (L=512 ). Suggest a suitable bit-by-bit multiplexing arrangement (as in Fig. 7.33c or d). What is the commutator frequency (in rotations per second), and what is the output bit rate