Find Lave for the letters X, Y, and Z and their probabilities .05, .05, and .9 and compare...

Find Lave for the letters X, Y, and Z and their probabilities .05, .05, and .9 and compare it to LHuf computed for single letters and pairs of letters, as in Figure 1. Does LHuf satisfactorily approximate Lave? How can we remedy the problem?

Figure 1 Improving the average length of the codeword by applying the Huffman algorithm to (b) pairs of letters instead of (a) single letters.