Question

How many strings of 4 lower case English letters are possible that have the letter "t" in them somewhere? Here strings may use the same letter more than once. (Hint: It might be easier to first count the strings that don't have a "t" in them.)

Answer 1

66351

Explanation:

The possible 4 letter words can be found simply as:

We know there are total 26 alphabets.

So total possible 4 letter words :

`26^(4) =456976`

4 letter words without 't':

`25^(4) =390625`

4 letter words with 't' = total possible 4 letter words - 4 letter words without 't'

4 letter words with 't' = 456976 - 390625=66351

4 letter words with 't' = 66351