1. Given the following lifetimes (weeks): 6.43 17.59 1.51 3.04 1.78 4.30 14.76 13.03 17.15 7.12 1.00 19.30 3.33 11.54 3.66 7.10 8.93 0.31 0.26 23.32 0.40 5.90 43.39 0.20 13.05 0.59 18.39 2.42 11.45 8.61 1.23 14.68 13.11 8.65 1.31 6.29 6.55 3.83 8.47 33.49 26.74 19.42 12.56 1.18 16.38 27.39 6.60 16.55 10.73 5.37 37.29 3.76 2.69 8.28 12.67 2.31 3.10 6.12 19.68 0.85 5.62 3.59 6.49 0.95 4.53 26.41 19.94 30.93 13.79 2.83 0.93 20.62 23.13 3.61 3.61 3.04 2.98 11.00 5.76 5.62 16.43 7.80 9.14 18.11 7.05 1.93 17.48 5.79 21.03 0.42 16.44 6.35 2.55 3.73 1.35 22.96 3.62 11.00 1.10 1.35 29.53 10.76 a) Compute the empirical survival function Sn (t) b) Estimate the probability that the lifetime is greater than 20 weeks.