I analyzed chain length distribution using HPAEC and fractionated my amylopectin sample into fa (DP: 6-12), fb1 (DP: 13-24), fb2 (DP: 25-36) and fb3 (DP > 36). For example, one of my sample recorded as fa=22%, fb1=43%, fb2=16%, fb3=19% and maximum detectable DP is 67. So how do I calculate the average chain length? Methodologies in published papers are not detail enough to understand the procedure. Any help please!