A group of tourists wants to visit only an even number of the four cities A, B, C, and D. How many travel itineraries can they make? All cities are connected to one another and please note that visiting the same cities in a different order counts as a different itinerary.
Choose the most appropriate option:
A) 20 B) 24 C) 28 D) 32 E) 36
The number of ways to choose two cities is 4C2=6.   The number of itineraries for each pair of 2 cities is 2!.   So the number of itineraries to two cities is  6*2= 
<gadget id="calculator"> 6*2</gadget>
<output>12</output>
12.   The number of ways to choose four cities is 4C4=1.   The number of itineraries for the group of 4 cities is 4!.   So the number of itineraries to four cities is 4!=24.   The total number of itineraries is   12+24= 
<gadget id="calculator">  12+24</gadget>
<output>36</output>
36.   The answer is 36.
<result>E</result>
A group of tourists wants to visit only an even number of the four cities A, B, C, and D. How many travel itineraries can they make? All cities are connected to one another and please note that visiting the same cities in a different order counts as a different itinerary.