BACK 6; LAY 6

[thunderfoot]

Horse Race of 12 runners.
Odds are :-
BACK LAY
3.9 4
7 7.2
8 8.2
8.2 8.4
9.4 9.6
11.5 12
21 24
22 23
34 38
38 42
75 80
150 160


If I LAY the first 6, the combined LAY odds are:- 1.22
If I BACK the last 6, the combined BACK odds are :- 5.92

Now if you were able to trade a single horse at those odds you'd be laughing all the way to the Bank.

Why is it that if I were to LAY the 1st 6 (at combined odds of 1.22) and BACK the last 6 (combined odds of 5.92), I can't make any money.

Been looking at this, on & off, for a while and can't get the 'maths' to calculate the BACK & LAY stakes, to 'prove' this doesn't work!!!

Help needed on the 'maths'!!!

[Captain Sensible]

Just treat everything in terms of laying to a fixed payout the same way as if you were laying a book.

i.e lay all runners t a fixed payout of £100 and back all to a fixed payout of £100
stake would be

lay £25.64 (100/3.9) @ 3.9 back £25 (100/4) @ 4
lay £14.28 @ 7 back £13.89 (100/7.2) @ 7.2

and so on

Basically your strategy is one tick trading on a lot of runners which will work sometimes when all bets get filled but it's likely they'll be a breach in one of the walls that may not come in or out to get one or more runners balanced.

[allgreen]

Why is it that if I were to LAY the 1st 6 (at combined odds of 1.22) and BACK the last 6 (combined odds of 5.92), I can't make any money

Thunderfoot, there is no 'trade' involved here because laying one half of the field and backing the other half is effectively just placing the same bet twice.

You will win with both bets when a horse in the second half wins the race and lose both when a fav wins the race.