2017/9-(iv) is like 2018/9-Q9-(iv),they all used definition of SSREG and SSRES. You may view seperate mean as yhat and overal mean as ybar. Put them into definition of SSREG and SSRES.
Yes, these are out of scope. I've now created a thread detailing all the old CT3 questions that are out of scope here: https://www.acted.co.uk/forums/index.php?threads/ct3-questions-that-are-out-of-scope-of-cs1.19125/
You're welcome. I confess I genuinely thought we already had a thread with this in - so sorry it wasn't done sooner.