To compare two treatments for solid tumors, researchers inoculated two groups of rats with a highly.

To compare two treatments for solid tumors,
researchers inoculated two groups of rats with a highly malignant neoplasm.
After the rats were randomized into the treatments, the survival (days) was
observed as follows:

Group 1, Drug A: 12, 16, 16, 18+, 19+,
20,28

Group 2, Drug B: 10, 14, 15, 18, 18,20+, 21

(a) Plot the survival curve for each group.

(b) Compute the product limit estimates of
these curves and the corresponding standard errors for each observed time.

(c) Use a statistical test to compare the
survival curves.