singular? plural?

[hitmewithgmat]

one of the most problematic ethnic groups..... (this question is from mgmat cat question with regard to Berlin Wall, so no hard feelings..)

anyway, how come this is a singular noun?

isn't it supposed to be plural?

one of the Noun(plural)... Plural Verb.

Please correct me.

thank you.

[awesomeusername]

ONE of the fastest cars is a Ferrari

Say the fastest cars in the world are a Maserati, a Ferrari, and a Bugatti.

A Ferrari is ONE of the fastest cars. ONE --> Singular.

[hitmewithgmat]

thank you, Awesomeusername!