[Tutor] Change datatype for specific columns in an 2D array & computing the mean

[Ek Esawi]

Ops..here is the text file.; previously i copied and pasted from either
Word or Excel.

AA,BB,CC,DD,EE
1,A1,B1,11.2,11/20/2011
2,A2,B2,2.5,10/21/2011
3,A3,B3,13.67,9/21/2011
4,A4,B4,14.2,8/22/2011
5,A5,B5,20,7/23/2011