If among \(n\) objects \(k\) are alike and the others are all distinct, the number of permutations of these \(n\) objects taken all together is \(n ! / k !\).

(a) How many permutations are there of the letters of the word class?

(b) In how many ways can the television director of Exercise 3.21 fill the 6 time slots allocated to commercials, if there are 4 different commercials, of which a given one is to be shown 3 times while each of the others is to be shown once?

Data From Exercise 3.21  

Transcribed Image Text:

3.21 In how many ordered ways can a television director schedule 6 different commercials during the 6 time slots allocated to commercials during the telecast of the first period of a hockey game?