Thanks for the reply Shaun. Yes, I wasn't sure about including the 16/17% into the calculation or whether it had already been taken out of the pool.

Now you've pointed it out the fact that three place dividends are paid makes it hard to work out.

I'm still wondering if a bet of $100 for the place on a horse paying $25.00/5.90 would destroy the dividend too much? It was actually paying something like $6.80 to place with 1 minute to jump.