Following are values of hash function for all keys
5 --> 5
28 --> 1
19 --> 1 [Chained with 28]
15 --> 6
20 --> 2
33 --> 6 [Chained with 15]
12 --> 3
17 --> 8
10 --> 1 [Chained with 28 and 19]
The maximum chain length is 3. The keys 28, 19 and 10 go to same slot 1, and form a chain of length 3. The minimum chain length 0, there are empty slots (0, 4 and 7). Average chain length is (0 + 3 + 1 + 1 + 0 + 1 + 2 + 0 + 1)/9 = 1