ROA=EBIT/Beg. Assets vs ROA=NI/Average Assets...WTF?

Why on earth is there a different calculation that uses EBIT in the numerator instead of NI to calculate ROA in the Granite Corp. example?

CFAI Volume 3

Study Session: 8

Page: 62

Paragraph: 1

I found this previous thread but it proved to be somewhat useless. Anyone have a good working theory?

My guess is that the Net Income version will be the only one present on the exam but it is definitely curious considering how big of a difference the ROA is between the two calculations.