Prove that every weighted average of three numbers x1 < x2 < x3 (with strictly positive weights) is less than x3. Do this by giving letter labels to possible weights for these numbers and comparing the weighted average of x1, x2, x3 to x3. Prove that every weighted average of three numbers x1 < x2 < x3 (with strictly positive weights) is less than x3. Do this by giving letter labels to possible weights for these numbers and comparing the weighted average of x1, x2, x3 to x3.