Three hundred identical cathode ray tubes (CRTs) placed into service simultaneously on January 1, 1976, experienced the following numbers of failures through December 31, 1988:

Year 1983 1984 1985 1986 1987 1988 Number of failures 13 19 16 34 21 38 Assume that there were no failures before 1983.

a. Based on these data, estimate the cumulative distribution function (CDF) of a CRT chosen at random.

Using the results of part (a), estimate the probability that a CRT chosen at random

b. Lasts more than 5 years.

c. Lasts more than 10 years.

d. Lasts more than 12 years.

e. That has survived for 10 years fails in the 11th year of operation.