No. of 4 letter words chosen from word with repeated letters

The number of 4 letter words that can be formed with the letters in the word EQUATION with at least one letter repeated is

9 Different letters of an alphabet are given. Find the number of 4 letter words that can be formed using these 9 letters which have (i) no letter is repeated (ii) atleast one letter is repeated.

Find the number of 4 letter words that can be formed using the letters of the word PISTON in which atleast one letter is repeated.

Find the number of 4 letter words that can be formed using the letters of the word ARTICLE in which at least one letter is repeated

Find the number of 4 letter words that can be formed using the letters of the word 'ARTICLE' in which atleast one letter is repeated.

A word of 5 letters is written down at random with the letters of the word COLLEGE. What is the probability that all the repeated letters were used?

A letter is chosen from the word 'PENCIL', what is the probability that the letter chosen is a consonant?

How many 4 letter words can be formed using letters in the word MADHURI if (a) letters can be repeated (b) letters cannot be repeated.

Ten different letters of an alphabet are given words with five letters are formed from these given letters. The number of words which have at least one letter repeated is