Data for tire life was described in Exercise 8-29. The sample standard deviation was 3645.94 kilometers and n = 16. 

(a) Can you conclude, using α = 0.05, that the standard deviation of tire life is less than 4000 kilometers? State any necessary assumptions about the underlying distribution of the data. Find the P-value for this test.

(b) Explain how you could answer the question in part (a) by constructing a 95% one-sided confidence interval for σ.