 mersenneforum.org Bayes's theorem example
 Register FAQ Search Today's Posts Mark Forums Read 2022-03-05, 13:18 #1 MattcAnderson   "Matthew Anderson" Dec 2010 Oregon, USA 5·233 Posts Bayes's theorem example Hi again, everyone who is interested in this content, I worked out a Bayes's Theorem example statistics Bayes's theorem probability P 0<=P<=1 where 1 is certain P(A|B) = [P(B|A) * P(A)] / P(B). in words, the probability of A choose B is dependent on the probability of event A, probability of event B, and probability of B choose A. common example from Chegg and others Suppose there is a school having 60% boys and 40% girls as students. The girls wear trousers or skirts in equal numbers; all boys wear trousers. An observer sees a random student from a distance and this student is wearing trousers. What is the probability of that this student is a girl? recall P(A|B) = [ P(B|A) * P(A) ] / P(B). example details P(G) = 0.4 where G is for girl P(B) = 0.6 where B is for boy P(T|G) = 0.5 probablity of wearing trousers given that the girl is a student, is 0.5 P(T|B) = 1 also, T is for trousers. Find P(G|T) this I can do quickly P(G|T) = P(T|Girl) * P(Girl) / P(Boy) looking above P(G|T) = 0.5 * 0.4 / 0.6. sure of that using calculator on computer desktop give the repeating decimal 0.3333333. This is one third. So, with confidence we see that P(G|T) is about 0.33. see Wikipedia for more explanation Bayes theorem Regards Matt ex engineer, ex school teacher, ex Navy, retired guy  Thread Tools Show Printable Version Email this Page Similar Threads Thread Thread Starter Forum Replies Last Post MattcAnderson MattcAnderson 2 2021-10-06 15:55 MattcAnderson MattcAnderson 0 2021-08-12 16:58 wildrabbitt Math 19 2019-06-22 14:32 Joshua2 Homework Help 15 2009-10-30 05:14 flouran Math 13 2009-05-26 19:12

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