4. the call letters for all radio stations in the united states start with either a w (east of the mississippi river) or a k (west of the mississippi river) followed by three other letters that
can be repeated. how many different call letters are possible?

 There are 35152  different call letters are possible.

Step-by-step explanation:

Given : The call letters for all radio stations in the United States start with either a W (east of the Mississippi River) or a K (west of the Mississippi River) followed by three other letters that  can be repeated.

i.e.The total characters = 4

The choices for first letter = 2  (either W or K)

The choices for rest of other letters = 26  (English alphabets has 26 letters)

Then, the number of different call letters are possible =2 x 26 x 26 x 26

=35152

Therefore , there are 35152 different call letters are possible.

$9.41

step-by-step explanation: