Five kinds of cola, it takes an average of 5/5 bottles to get one of the five kinds.
Five kinds of colas, it takes an average of 5/4 bottles to collect one of the four kinds.
Five kinds of cokes, it takes an average of 5/3 bottles to get one of the three.
Five kinds of colas, it takes an average of 5/2 bottles to collect one of the two.
Five kinds of colas, it takes an average of 5/ 1 bottle to collect one of them.