Recharge/fast cast items, do they stack?

Say, I have a wand that gives 20% chance faster Spawning recharge, and a focus that does the same. Do I now have 20% chance faster recharge (doesn't stack), 40% chance faster recharge (linear stack), or 36% faster recharge (probability stack, basically 2 chances, or 1-(1-.2)^2)

If the same type don't stack, how about if you have one that gives 10% to all spells, and a 20% to a specific line? Does it stack then?

And while we're on it, do the Ritualist faster cast/recharge work on binding rituals? Thanks!

http://www.guildwarsguru.com/forum/s...d.php?t=119826

a bit about stacking...

They do stack. 36% (probability stack) is correct. 100% - (80% chance of an 80% chance), as you said. So a 10% wand + 20% focus would give you 28%. That's why a 20/20 Rockmolder is the luv, you can combine it with anything, for example Smiting spells which don't have a high-end focus.

Wow, interesting chart, Jedi. I never knew quarter-casting was possible. Extremely rare, but cool...

36%.

Or more precisely, 32% chance of fast recharge, and 4% chance of really fast recharge. It's possible for both bonuses to trigger on the same cast. Which is awesome.

Alright thanks, that helps my decision on what to get.