Question

How many different 4-letter radio station call letters can be made if thr first letter must be K or W, repeats are allowed, but the call letters cannot end in an O?

Answer 1

By using 26 letters of the alphabet we have to make 4-letter radio station call letter.

Since, first letter can be made only by using K or W so we can made this by 2! = 2*1=2 ways.

And, since, the repetition are allowed so, 2nd can be made using 26ways and 3rd letter can also made using 26 letters.

Now, the 4rth letter of 4- letter can't be end with O so, we are left with (26-1) = 25 letters therefore we have only 25 ways to make 4rt letter so, altogether we have 2*26*26*25 = 33,800 ways.