There are n cities. What is the number of airlines that connected 5 different cities (airline from city A to city B is different with airline from city B to city A)? Choose the correct option:  A) n(n-1)  B) n(n+1)  C) n(n-1)/2  D) n(n-3)  E) n2
First of all, the possible number of airlines is n. Then, the possible number of airlines departing from one city to another becomes (n-4). Hence, the answer is n(n-4), which makes A an answer choice.   n(n-3)
<result>D</result>
There are n cities. What is the number of airlines that connected 5 different cities (airline from city A to city B is different with airline from city B to city A)?