Segmented Sharpe ratio

Example on page 237 gives segmented sharpe ratio and global Sharpe ratio. They use segmented Sharpe ratio when solving for segmented risk premium and global sharpe ratio when solving for intergrated risk premium. Last year we used Global Sharpe ratio when solving for both integrated and segmented risk premium.

Does this mean past essay exams on Singer are no good because they don’t give segmented sharpe ratio?

And is equation 5 written wrong on page 236?

Thank you.

Looks right to me