1. (20 points) For the following survival data with "+" indicating censored subjects::

1.2, 1.8, 2.0, 2.1+, 2.9, 3.0+, 3.4, 4.0+, 4.1, 14.2,

(a) Produce a plot of the Nelson-Aalen estimator for the cumulative hazard function for T.

(b) Assume that the data is exponentially distributed, what's the MLE of the survival function of T at time T = 3.4.

please use R code and explain each part to help explain. In this problem the data used in R is build in it's the "survival data)