comprehension!

a) and b) parts seem fine to me. In b) they have basically asked that if you fix the first two numbers of the sequence, how many sequences can you form after those two. c) ka I don't know.

SPECIALLY a part of my discussion with abhirup [ :P :P]

for solving (c) i took the following way....choose any two of the entries and then they will be at a distance of TWO if they have these two entries with values different form the original one!which can happen only in TWO ways for each of the two entries

SUPPORTING EXAMPLE:::

suppose we selected following TWO entries in the ternary sequence so we have:::
[0,1........................] as original sequence

now entries at distance TWO from above are
[1,0]
[1,2]
[2,0]
[2,2]

i.e. 2*2=4

so answer for the part (c) should be 10 C 2 * 2 * 2!