Khan/khan-exercises — Issue #10108: Probability 1 - Probability 1
Author: KhanBugz
Created: 2012-01-03 16:52:17+00:00
State: open
Labels: firefox, hard, win7

Reporter: fantasycomedian@gmail.com

I don't understand how to work the problem without having to flip a coin and label all the possibilities or having to guess all the time. I don't know how to work out these problems systematically and correctly. I thought I was doing it the way that the video "Getting at Least One Head" showed but now it is very confusing and I don't know of the universal way to do it.

[probability_1.html?seed=2&problem=2](http://sandcastle.khanacademy.org/media/castles/Khan:master/exercises/probability_1.html?seed=2&problem=2&debug)

[Answer timeline](http://sandcastle.khanacademy.org/media/castles/Khan:master/exercises/probability_1.html?seed=2&problem=2&debug&activity=%5B%5B%22incorrect-activity%22%2C%22%5C%221%2F4%5C%22%22%2C18%5D%2C%5B%22incorrect-activity%22%2C%22%5C%221%2F2%5C%22%22%2C8%5D%2C%5B%22incorrect-activity%22%2C%22%5C%227%2F8%5C%22%22%2C24%5D%2C%5B%22hint-activity%22%2C%220%22%2C4%5D%2C%5B%22hint-activity%22%2C%220%22%2C5%5D%2C%5B%22hint-activity%22%2C%220%22%2C5%5D%2C%5B%22hint-activity%22%2C%220%22%2C5%5D%5D)

["1/4","1/2","7/8"]

Mozilla/5.0 (Windows NT 6.1; WOW64; rv:8.0.1) Gecko/20100101 Firefox/8.0.1

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