Scrolling probability chart and excell questions

I made such tables already using scrolls of only 1 type. It's in my LOLPALLY guide under the scrolls appendix xD. Chance of booming with only 70% scrolls is actually pretty high when you pile them on a 7 slot equip o.O

common sense. with a 50% destruction rate and a 30% pure-fail rate, it sucks. ive not once lost an expensive item thanks to a 30% scroll, not once, even the ones i stupidly scrolled. but, 70%'s?
lost a clean maple shield, level 30 maple hat, my then 9 slot enig with a 30% passing on the first slot, countless weapons, the list goes on.

rule of thumb ive made is use 30/60, sell 70, junk 10/100. =/