2. (30 points) Listed below are values of survival time in years for a set of subjects. Right- censored times are denoted with "+" as a superscript. 0.4,1.2,1.2, 3.4, 4.3,4.9,5.0,5.0+, 5.1, 5.1+,6.1, 7.1 (a) (10 points) Let S(t) and S(t) denote the Kaplan-Meier estimator and the Fleming- Harrington estimator of the survivorship function of the event time, respectively. Calculate S(7) and S(7) by hand. (b) (10 points) Figure 1 below plots the Kaplan-Meier estimates for two subgroups of these subjects separately. Based on the figure and the times listed in part (a), list the event and censoring times for each group separately