Can someone please give a more detailed solution to this problem? I understand the problem up to p^30(1-p)^13. How do you get the p^30? Wouldn't it be p^20? Then how do you find that the maximum of p is 20/33? The solution the Soa gives is unclear and skips a lot of the steps. If someone can please help fill in the missing pieces, it would be much appreciated!! Thanks!
Soa sample question 44