25. Refer to Exercise 21. Instead of selecting n  20 helmets to examine, suppose we examine helmets in succession until we have found r  3 awed ones.

If the 20th helmet is the third awed one (so that the number of helmets examined that were not awed is x  17), what is the mle of p? Is this the same as the estimate in Exercise 21? Why or why not? Is it the same as the estimate computed from the unbiased estimator of Exercise 17?