gate13 Posted April 26, 2015 Posted April 26, 2015 (edited) hi i have a table and one of the questions is P(X≠Y) I am so confused! does this mean is the same as Pr[X∪Y ] which means : Pr[X⋃Y ]=Pr[X]+Pr[Y]-Pr[X ∩ Y] Please help ! for example the table is something like that: y x 1 2 3 4 1 0.02 0.02 0.02 0.04 2 0.04 0.04 0.04 0.08 3 0.14 0.14 0.14 0.28 Edited April 26, 2015 by gate13
timo Posted April 26, 2015 Posted April 26, 2015 Depending on the context there may be different interpretations. The simplest one would be the following. You take a random variable x and a random variable y. The probabilities for each combination are given in your table. Question: What is the probability that x and y do not have the same value? Sidenote: Strictly speaking is it impossible to answer questions about mathematical expressions when the meaning of the letters that appear is not given. Effectively, their meaning can often be assumed - e.g. in the context of a physics problem with only one body one often assumes that "m" means the mass of the body. But for X and Y (capital letters) combined with a table that lists x and y (non-capital letters) assuming things about the meaning from only the letters is highly speculative.
Sensei Posted April 26, 2015 Posted April 26, 2015 (edited) 2 dimensional table should be table[][] not table[]. 2d table can be squashed to 1d table by f.e. table[y*columns+x] Are you mathematician who want to write computer program? Equality operator in computer programs is == Not-equal operator is != Edited April 26, 2015 by Sensei
gate13 Posted April 26, 2015 Author Posted April 26, 2015 Sensei, you are off the topic!sorry! timo!!!! all the letters are X and Y... They are all capital! Never mind guys!
Sensei Posted April 26, 2015 Posted April 26, 2015 This is computer science forum, so you're off-topic. I see no computer programming related questions in your post..
gate13 Posted April 26, 2015 Author Posted April 26, 2015 (edited) Yes, this is a topic in one of my computer science classes..... did you know math and computer sicence were related? lol Edited April 26, 2015 by gate13
imatfaal Posted April 27, 2015 Posted April 27, 2015 you have a table of outcomes - 12 in all - that give the probability for any of three x outcomes and four y outcomes; check that the total comes to 1. Those in which x give same outcome as y ie x=1 y=1 should be excluded - the remainder is the probability that x =/= y
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