The following failure times (in days) have been recorded in the proof test of 20 units of new product: 2.6, 3.2, 3.4, 3.9, 5.6, 7.1, 8.4, 8.8, 8.9, 9.5, 9.8, 11.3, 11.8, 11.9, 12.3, 12.7, 16.0, 21.9, 22.4, 24.2
a) Make a graph of F(t) vs. t
b) Make a Weibull probability plot and determine the scale and shape parameters
c) Make a lognormal plot and determine the two parameters
d) Find out which of the two distributions provides the best fit to the data, using the coefficient of determination as a criterion.