Basic arrangements with repeated letters

Questions asking for the number of arrangements of letters from a word containing repeated letters, with no additional constraints beyond arranging all or some of the letters.

1 questions

CAIE S1 2018 November Q1
1
  1. How many different arrangements are there of the 11 letters in the word MISSISSIPPI?
  2. Two letters are chosen at random from the 11 letters in the word MISSISSIPPI. Find the probability that these two letters are the same.