Question 853269
Since this is multiple choice, check each answer from term to term.  A term times the common ratio equals the next term.<P>
A: 1/3:  1/4 * 1/3 = 1/12.  That's not the second term.  Eliminate answer A.<P>
B: 3/4:  1/3 * 3/4 = 3/16.  It works as a ratio between the first and second term.<P>
3/15 * 3/4 = 9/64.  Good for third term.<P>
9/64 * 3/4 = 27/256.  Good for fourth term.<P>
27/256 * 3/4 = 81/1024.  This ratio works for all terms, so the answer is b.<P>
You can also divide each term by the previous term to find the common ratio.  If the common ratio between terms is the same, then it's a geometric sequence, and you have the common ratio.<P>
81/1024 divided by 27/256 = 81/1024 * 256/24 = 3/4.  Do the same for each pair terms to find that the common ratio between all terms is 3/4.