Solution
= Solution
Apply <Huffman coding>. Combining weights
$$
.02+.03=.05,\quad .04+.04=.08,\quad .05+.08=.13,\quad
.13+.14=.27,\quad .27+.28=.55
$$
gives, for example,
$$
x_1:0,\ x_2:10,\ x_3:110,\ x_4:11110,\ x_5:11111,\ x_6:11101,\ x_7:11100.
$$
Any consistent interchange of siblings is equivalent.