Answer: They can visit all 5 cities in 120 different ways
Step-by-step explanation: If the family has the option of visiting five different cities in Europe, and they intend to visit all of them, then they can visit any one first and go on to another one, and so on till they exhaust all their options.
However, there is the option of which to visit first, which to visit second, and so on. This means if they decide for example, to start with Athens then they may decide to visit any of the four other cities afterwards in more than one way, and this is because all the other four cities equally have the option of being number two. So with Athens at number one, we have the other four equally likely to be number two, and so on.
To make this less cumbersome, we shall apply the formula for permutations. Rather than counting numbers of arrangements like described above, Keisha's family can use the permutation formula which is;
Pₙ = n!
Where n is the number of available options,
P₅ = 5!
P₅ = 5 x 4 x 3 x 2 x 1
P₅ = 120
Hence, the family can arrange their trip to Europe in 120 different orders
