Nine samples = were extracted from the parts delivered by the reliability engineer, and the failure time data as a result of the life test were as follows. (0.7, 2.0, 5.0, 8.0, 15.0, 23.0, 40.0, 43.0, 50.0) (unit = time) Test whether you followed the normal distribution by RBI, estimating the parameters (means, standard deviation), and observing the results RBI in the probability paper. (F(t) uses the mean ranking method)