Question: A triangle has angles A, B, and C (in degrees). The angles are estimated, using a certain device, giving independent estimators XA, XB, and XC, which are all normally distributed,with the correct mean, and standard deviation equal to 1, i.e.
XA ~N(A, 1), XB ~N(B, 1), XC ~N(C, 1).
For a certain reason, interest lies exclusively in angle A. To estimate A, we use
Yw = w*XA + (1 - w)(180 - XB - XC), and we get w=2/3.
suppose that XA XB AND XC are observed to be 61,91 and 32. Find a 95% confidence interval for A based on XA XB and XC.