In 1912, the U. S. government began issuing licenses to radio stations. Each station was given a unique three-letter call sign. Radio stations in the western United States were given call signs starting with K. Stations in the east were given call signs starting with W. For example, the radio station with the call sign ABC is KABC in California, and WABC in Georgia. a. How many different three-letter call signs are there?

Hint: don’t worry about the K or W – just find the number of ways to arrange any 3 letters

b. How many different three-letter call signs are there where the first letter is a D?

Hint: again, the K and W don’t matter

c. In a random selection of radio station call signs, what is the probability of selecting a radio station with a call sign that starts with the letter D?