14.9 In the previous two problems we found the posterior distribution of the slope of y on x, the rate of weevil infestation for endophyte infected and noninfected ryegrass. Let be the slope for noninfected ryegrass, and let /32 be the slope for infected ryegrass

(a) Find the posterior distribution of P1 - P2.

(b) Calculate a 95% credible interval for P1 - ,&.

(c) Test the hypothesis HO : - P2 5 0 versus HI : - /32 > 0 at the 10% level of significance.