For pentan-3-one why is the splitting pattern of the peak with greatest area in the high resolution nmr spectrum a triplet and not a quintet?

There are TWO sets of protons observed in the #""^1H# #"NMR spectrum"#....the methyl groups, which arise from the #6H# of the methyl chain termini, and the #4H# of the methylene protons. The methyl protons are coupled to the 2 methylene protons, and so we should see a triplet. And given this coupling the methylene protons should appear as a quartet...i.e. the #2n+1# for simple first order spectra.

As always, integration helps us to differentiate the signals....the most intense peak arises from the most numerous protons...the six methyl protons....versus the 4 methylene protons...i.e. a #3:2# integration ratio

How many signals would you see in the #""^13C{""^1H}# #"NMR spectrum"#?

PS.

Please note for the better informed....yes I know that these protons are not magnetically equivalent...I am not going to open that can of worms here. You are welcome to do so, but this is probably a 2nd year question.

The #""^1H# #NMR# spectrum of #"diethyl ketone"# was included at the kind suggestion and direction of Truong-Son N. ..many thx. The given spectrum does not include integration data, but we will have to bear that cross...