Here are some relevant calculations to illustrate important but poorly understood concepts of Exotics.

I'm using these formulae:

a*b*c/(1-a)/(1-a-b) = Trifecta Prob

a*b*c*d/(1-a)/(1-a-b)/(1-a-b-c) = F4 Prob

First assume a ZERO-rake situation:

And that a, b, c and d are all paying as 10% chances.

But you know that they are 10% better than that - i.e. 11% chances

You can (as KV did) approximate your expected return by multiplication.

133.1% Trifecta
146.4% F4

But if you use the formulae above you get:

138.1% Trifecta
158.7% F4


Now apply the offical rakes of 21% and 25% to get a post rake:

109.0% Trifecta
119.0% F4


Leading to the intriguing situation where the F4 profit is over double that for the Trifecta even though the F4 rake is higher.

If you change the parameters you can get even more startling results.

For KV's case where he claims to be 18% better:

138.7% Trifecta
168.4% F4

Suggesting even better returns for the F4.

The figures get even weirder when you consider say 20% chances, but anyone interested can readily calculate such things on a spreadsheet.