Below are the Intervals from primary AIDS diagnosis until death for a sample of 12 hemophiliac patients at most 40 years of age at HIV seroconversion.

ID      Survival (months)

1                2
2                3
3                6
4                6
5                7
6               10
7               15
8               15
9               16
10             27
11             30
12             32

(a) Use the Kaplan-Meier (product-limit) method to estimate the survival function.

(b) Construct a survival curve based on the product-limit estimate.

(c) Estimate the median survival time