A computer system uses passwords that contain exactly eight characters, and each character is 1 of the 26 lowercase letters (a-z) or 26 uppercase letters (a-z) or 10 integers (0-9). let s denote the set of all possible passwords, and let a and b denote the events that consist of passwords with only letters or only integers, respectively. determine the number of passwords in each of the following events.
(a) 9
(b) 52
(c) 62
(d) More than 26 but less than 62