Actually my field of study is mathematics and I really like it.I do iT jobs near my study.I have faced a hard question in statistics which you may be able to solve it ! Leave comments if you got an idea.
Consider a reliability inspection policy where n items are put "on test" and the first r failure times, T1,T2,. . .,Tr are recorded. Assume the pdf ( probability density function ) describing the response variable is exponential with parameter Lamda.Write down the appropriate joint pdf, differentiate it and show that MLE ( Maximum Likelihood Estimation ) for Lamda is given by : (1/r)*(T1+T2+. . .+Tr)+(n-r)*Tr.