5 rolls 1/18 chance
I have 5 chances to get the item i want from a chest. There are 18 items in the chest
I want a specific one. Whats the percentage i will pick it out randomly.
+247 well, to figure this out we actually have to figure out the chance that you won't get the item you want and then work out what are the chances you will using that. This working out assumes that for each item you pick there is one less item in the chest. i am rounding to the nearest 100th.
first, the chance that you will fail is 17/18. the chance you will do it on this try is 1/18*100=%5.56
then, fail=16/17. 1/17*100=%5.88 5.88+5.56=%11.44
rinse and repeat. fail=15/16. 1/16*100=%6.25 11.44+6.25=%17.69
again. fail=14/15. 1/15*100=%6.67 17.69+6.67=%24.36
Finally, fail=13/14. 1/14*100=%7.14 24.36+7.14=%31.5
so there you have it. your chance of succes is %31.5, roughly a 1/3 chance. 
