My answers:
The right sequence is:
1. H7
2. H6
3. H3
4. H1
5. H2
6. H4
7. H5
ANSWERS:
1. D
2. C
3. A
4. B
5. A
Will edit the post in a few moments for the solution
PS EDIT:
I had a few issues which confused me. This is a very tough problem
First, we cannot have a guy who can make exactly 6 correct bets because one bet is automatically wrong this way. Hence, there is a guy who makes all 7 wrong bets and a guy who makes a maximum of 5 right bets.
These lines in the question were quite confusing this way:
(1) Every horse was bet upon correctly by at least 1 person &
(3) No person got all seven bets correct.
Now that we know one person made a maximum of 5 right bet, we need to find that guy who makes 5 right bets. Let us assume its
A but then A doesn't give the requisite combination of 0,1,2,3,4,5 right bets. Then lets go to
E. He gives us the maximum variety in the bets. Now we only need to shuffle 2 of E's bets such that we get a combination of 0,1,2,3,4,5 right bets. It is for sure that E makes 5 (which is maximum) right bets.
Now the question is how do we select 2 of E's bets and interchange them. Let us select those pair of bets which are interchanged in other guy's set of bets. Look at H3 and H1's position in E's set. They are at position 3 and 4 respectively. Now this pair of choice is at posiiton 4 and 3 respectively in F's set of bets. Now let us go about checking whether this satisfies all our conditions. But it doesn't.
So now let us hunt for another such combination. Take H5 and H7 from E's set of bets. They are at positions 1 and 7 respectively. Now this pair of horse position is at position 7 and 1 respectively in B's set of bets. Hence we can narrow down that this maybe the right set of bets when we interchange only the position of 5 and 7 in E's set of bets.
Hence, I can come down to the following set by tweaking the positions in E's set of bets:
H7
H6
H3
H1
H2
H4
H5
Now this combo gives us the following results:
A makes 1 right bet which is H3 position 3
B makes 2 right bets which are H7 and H5 at position 1 and 7 respectively
C makes 3 right bets
D makes 4 right bets
E makes 5 right bets
F makes 0 right bets
I hope this solution makes sense

Nishant