95% Confidence Interval for Regression Coefficients Question

Hello all,

I have been trying to figure out how to answer these homework questions for far too long and happened upon this forum with hopes that I could get a nudge in the right direction…Here is the problem as an attachment.

Also included is my work thus far…I think my issue is that I am having a hard tome identifying what ß1 is…

Any help would be greatly appreciated. I feel that this should be so simple, but I lack the knowledge of knowing where to even start with this problem…

It would be great if I could see an example for both 11.7 and 11.8! ^^