ああ母平均じゃなくて母分散なのね。母分数でもなくて。

> 11*var(c(38.0,37.5,35.1,38.3,36.3,37.8,36.8,35.9,37.7,38.2,35.7,38.6))/c(qchisq(0.99,11),qchisq(0.01,11))
[1] 0.5989559 4.8499243

これ出せばおｋ