
Probability and Statistics Basic Probability and Statistics Math Forum 
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March 6th, 2016, 07:07 PM  #1 
Newbie Joined: Feb 2016 From: Illinois Posts: 8 Thanks: 0  How do I find the Mean and Standard Deviation for this probability
According to newspaper reports, there have been 4 notable airplane crashes in the last 8 months, e.g., Kennedy’s crash, Alaskan Air crash, etc. What is µ and standard deviation as expressed in 3week units? 
March 6th, 2016, 11:23 PM  #2 
Senior Member Joined: Dec 2012 From: Hong Kong Posts: 853 Thanks: 311 Math Focus: Stochastic processes, statistical inference, data mining, computational linguistics 
There are around 11.6 threeweek units in eight months, so I guess the mean is roughly 0.3442 per threeweek unit. As for standard deviation, I'm not sure we can calculate the SD without knowing which crash happened in which 3week unit. Can we assume the underlying distribution is Poisson, in which case var = mean? 

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deviation, find, probability, standard 
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