It is known from past information that the probability of failing to finish an Ironman (called a DNF) is 15%. Suppose we take a sample of 100 Ironman races over the past few years and find that the DNF percentage is 12%. We are interested in seeing if there has been a significant decrease in the number of DNFs. Use alpha=0.05. Find the 95% confidence interval for the percentage of DNFs.

a. (0.0665, 0.1735)

b. (0.0555, 0.1845)

c. (0.1179, 0.1221)

d. (0.0563, 0.1837)