n class, we saw how to use survey package to compute y and t under SRS and STSRS. We also saw how to use use that package to compute VSRS( y), VSRS(t), VSTSRS( y) and VSTSRS(t). However, the survey package must be able to compute y and t, as well as their corresponding variance estimators, under more sampling designs that just SRS and STSRS. Hence, the survey package uses more general formulas than the ones given in class. However, these more general formulas simplify to the ones given in class, and this question is concerned with proving this