Why is George 乔治 in Chinese?
About the "乔" part of "George[dʒɔ:dʒ]", you can find some material in the 译音表(the Form of Ttransliteration). Besides, "奇" should be instead of "治" following the form. 


However, "约定俗成(the convention)" is one of the important rules of 《英文人名翻译准则》. Everybody often use "乔治" refer to "George", so that "乔治" is agreed upon gradually. Anyway, I don't know why did the first person call "George" "乔治".

Download 英语姓名译名手册(商务印书馆 第四版).pdf