Re: Explanation for 119

I understand all of the explanation except the initial determination of peaks. Why are there 3 peaks? I thought there would be 5 peaks. What happens to the hydrogens attached to C1 and C4?
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Sorry that I didn't respond to this earlier -- I didn't realize that the question had been put as a comment on the previous one.

The hydrogens on C1 are part of the two methyl groups bound to C-2. While, in nomenclature, we would distinguish this carbon from the carbon in the methyl group on C-2, you can see that they're actually equivalent.

Please check out my unparalleled MS Paint skills that show the three groups of protons by color: