Put this in Excel

=LN("Number of races")/-LN((1-"Strike rate as a decimal"))

For a 35% strike rate over 10000 races

=LN(1000)/-LN((1-0.35))

Longest out would be 21.38

__________________
Pixie

"It's worth remembering that profit isn't profit until it's spent off the racecourse." -- Crash