測量~加權中誤差 請大大幫忙解惑一下

如照片
請問一下 那個裡面加權後 開根號 幾乎都會比 改正數來的大很多?
請問一下我這樣算對嗎!?
那 加權後 要如何判斷 錯誤值!?
NBA 寫:Hp1 = 143.425 + 26.672 = 170.097m
Hp2 = 217.580 – 47.466 = 170.134m
Hp3 = 168.724 + 1.374 = 170.098m
[權]
(1/7.8):(1/17.8):(1/12.3) = 243.54:95.94:154.44
[最或是值]
Hp = (170.097*243.54 + 170.134*95.94 +170.098*154.44) / (243.54 + 95.94 + 154.44)
= 170.1045m
[改正數]
v1 = 0.0075
v2 = -0.0295
v3 = 0.0065
[單位權]
σ = ± {[(170.097*0.0075^2) + (170.134*-0.0295^2) + (170.098*0.0065^2)] / (3-1)}^(1/2) = ± 0.2871m
v 不能大於σ~3σ
符合檢錯ok!
[中誤差]
m = ± 0.2871 / [(3)^(1/2)] = ± 0.166m
[答案]
Hp = 170.1045m ± 0.166m