Hi there, Can someone please explain the following algebra. In the solution, to part (i), when getting the updated the estimate for E(s^2(theta)), there's one part where the last two terms are added together to simplify the expression. Please if someone could explain, that would be great. Please see the picture attached. Thanks a lot, Tom
I'm confused - are you just asking how \(-2\bar X_I \sum\limits_{j=1}^{10} P_{Ij} X_{Ij} +\bar X_I^2 \sum\limits_{j=1}^{10} P_{Ij}\) becomes \(-\bar X_I^2 \sum\limits_{j=1}^{10} P_{Ij}\)? In which case, all that has happened is they have rearranged the given result to \(\sum\limits_{j=1}^{10} P_{Ij} X_{Ij} = \bar X_I \sum\limits_{j=1}^{10} P_{Ij}\) and substituted it in.
