Q4: [6 points) a) If a dictionary-based compression algorithm is used. Assume the average number of characters per word is 6, and the dictionary used contains 4096 words. Find the average compression ratio that is achieved relative to using 7-bit ASCII codewords. [1+1+1 points] [A1, B1, C1] b) In most multimedia applications involving audio, the bandwidth of the communication channel is less than the source rate. If it is difficult to use a compression algorithm, discuss the alternative solutions and their consequences in terms of system complexity and recovered audio quality. [1+1+1 points] [A1, B1, Cl]