You are given a geometric progression (bn), for which b4 = 6, b5 = 2. Find the denominator of the progression.

Before us is a decreasing geometric progression, since here are two consecutive terms, and the next term is less than the previous one. Thus, our denominator should not be an integer, but a fractional number.

So, in order to find the denominator in a geometric progression, it is necessary to divide any member of this progression by the previous term. We are lucky: we are given two consecutive terms, so it will be very easy to do:

2: 6 = 2/6 = 1/3.

So 1/3 is the denominator.