recall that the terms of a geometric series are given by:

for

where is the nth term, is the first term, is the common ratio, and is the current number of the term.

here we see that and

solve for and you can find the middle term.

here you haveOr this one:

_____,_______,_______,2.5 r=2

My textbook doesn't go over this either....

Thanks

solve for and you can find the other terms