NMR question

[ktran17]

http://imageshack.us/photo/my-images/818/afafafp.jpg/

How come Hb is denoted as a multiplet (triplet)

I understand that its near two unequivalent hydrogens and therefore complex splitting would occur. But, shouldnt it be multiplet (doublet of doublet)

I know for a fact when you're near two or three adjacent protons the n+1 rule applies only if they're all equivalent. But the two hydrogens near Hb are not =[

The answer says its a multiplet and therefore acknowledges that complex splitting occurs though.. maybe chad made a mistake?

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[penny49]

I think for H NMR
there are 3 singles
from button H to top: triplet, doublet of triplet, triplet

 

[lutopie0730]

looks like doublet of doublet to me, too.