LJP07 7,047 Posted April 27, 2012 Report Share Posted April 27, 2012 I don't even know if this question makes any sense or not. I was asked by an individual I know, and couldn't give an answer as I'm not mathematically minded; If there's a 70% chance of an event happening in the next 30 minutes, and there's a 15% chance of it happening in the next 5 minutes, then what's the overall probability? Again, I don't know if it makes any sense or not, and haven't a clue to even approach it or determine it as wrong. I was wondering if anyone here could provide me with some clarification. :) Quote Link to post Share on other sites

CraigD 398,738 Posted April 29, 2012 Report Share Posted April 29, 2012 The phrase “overall probability” is a bit too vague for me to comfortable answer a question about. However given the 2 probability data in your example I can calculate one more datum: Where [math]p_{(0,5)} = 0.15[/math] and [math]p_{(0,30)} = 0.7[/math] [math]p_{(5,30) = \frac{ p_{(0,30)} p_{(0,5)} }{ 1 -p_{(0,5)} } = \frac{ 0.7 \cdot 0.15 }{ 1 -0.15} } = \frac{11}{17} \dot= \,0.6471 [/math] That is, the probability of the event happening between 5 and 30 min from now is about 64.71% That’s all I can think of to derive from the given data. Quote Link to post Share on other sites

phision 4,148 Posted June 9, 2012 Report Share Posted June 9, 2012 (edited) The phrase “overall probability” is a bit too vague for me to comfortable answer a question about. ' The summation can be interpreted as a weighted average, and consequently the marginal probability, , is sometimes called "average probability"; "overall probability" is sometimes used in less formal writings.' - http://en.wikipedia....ility#Statement If there's a 70% chance of an event happening in the next 30 minutes, and there's a 15% chance of it happening in the next 5 minutes, then what's the overall probability? This is a logic problem and with many logic problems the answer is in the question! The "overall probability" will be the same as, "a 70% chance of an event happening in the next 30 minutes". The "15% chance of it happening in the next 5 minutes" statement, only serves to complicate the the information given and distract you from the answer. I think probabilities are usually presented as decimal numbers from 0(zero will never happen) to 1(one will actually happen), so the answer will be: 0.7 within 30 minutes. Edited June 9, 2012 by phision Quote Link to post Share on other sites

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