12742
Results : Students ' mean age was 19 . 9 +/- 0 . 9 years , and of all the students 74 ( 78 . 7 % ) were undergraduate students ; remaining 20 ( 21 . 3 % ) were graduate students .
 None
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 None