二、試回答下列問題：
⑴有兩箱機械軸，每箱內各有 10 件，每支軸的直徑規格要求表示為 250.042 mm。A 0箱內各軸徑的容差（tolerance）測量尺寸為：0.01,0.01,0.02,0.03,0.05,0.05,0.05,0.06,0.06,0.07（mm）。B 箱內各軸徑的容差測量尺寸為：0.02,0.03,0.04,0.04,0.04,0.05,0.05,0.05,0.06,0.07（mm）。試問各箱內軸徑容差的平均值（mean value）、樣品標準偏差（sample standard deviation），及變異值（variance）？若需自這兩箱中購進一箱，試問如何選擇 A 箱或 B 箱？（9 分）