A dms has an alphabet of five letters xi i 1 2 5 each

Question

A DMS has an alphabet of five letters xi, i = 1, 2,..., 5, each occurring with probability 1 5 . Evaluate the efficiency of a fixed-length binary code in which

1. Each letter is encoded separately into a binary sequence.

2. Two letters at a time are encoded into a binary sequence.

3. Three letters at a time are encoded into a binary sequence.