點係graph到畫standard deviation bar?? 用手畫 NOT excel!
Temperature / °C
20
23
30
40
50
Mean
4.1
3.9
6.5
7.1
8.4
Standard Deviation (SD)
0.09
0.09
0.22
0.15
0.09
好似呢幅圖, ''工''字咁個個
http://www.rit.edu/cos/uphysics/graphing/Linear.gif