a) Given a string consisting ofl characters 'a'..'z' (no repetitions) in some order , what is the probability' that 'a' and z\" are next to each other? {i.e. \"as" or \":a") Hint: to nd the size of E, can we compute the number of possible strings if we treat \"as" as a special character that replaces 'a' and '2\"? b} Given a string consisting of 26 characters 'a'.. '2' [no repetitions) in some order , what is the pro- babilitvr that it contains 13 characters [N GRDER'? {i.e. \"abcde...", or \"Iicdei'.. .n\