We give the maximums and the minimums of a class of overall survival functions in case where marginal distributions are fixed. The theory of copula, especially, the Fr\'{e}chet Hoeffding upper and lower bounds play a crucial role. We also give an application to the education system in case where marginal distributions are Weibull distributions. In particular, we discuss at least how many new employees per an expert we need to transmit technology in Japan. Our result can be applied to any country with social data.
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