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View Full Version : Check my math on these two probabilties, please


twistedbeats
02-16-2005, 10:42 AM
Warning, i dropped prob and stat.

1)if the odds of an event happening are 1 in 8, what are the odds of it not happening in 13 tries:

(7/8)^ 13 = .17624

2) what are the odds of the same event happening exactly two times in 18 trials

(1/8)^2 * (7/8)^16 * 18 choose 2= .282254

gaming_mouse
02-16-2005, 01:01 PM
Correct. The only thing to note here is that you have assumed the events are independent.