What is the probability of getting a license plate that has a repeated letter or digit if you live in a state that has three numerals followed by five letters followed by one numeral? (Round to the nearest whole percent.)

Answer 1

number of all possible plates
=10^3 * 26^5 * 10
= 118813760000 (this includes all types of repetition)
number of plates without any repetition
= 10*9*8*26*25*24*23*22*7
3.9783744 x 10^10

so prob of some kind of repeat
= 1 - 3.9783744 x 10^10/118813760000
= .665