Hapaha: I see it as meaning Half of Half, or a quarter. That may not be its origin, but it makes the word easier to remember.
I see it as hapa (part) ha (eha 4) = one of 4 parts.
Hapakolu would be 1/3.
Marked wrong for "Ten fifteen"?
Itʻs the difference linguistically between a quarter hour and fifteen minutes. Analog vs digital. :-)
Marked incorrect for: "Fifteen minutes past ten." ...
Also for "a quarter after ten."
Did you report it?