<image>(2014 Spring • Guangning County School Midterm) Answer the following questions based on the statistical chart:

\frac{}(1) In the statistical chart, one small grid represents ____ trees.
(2) The class that planted the most trees in the third grade is class ____, and the class that planted the least trees is class ____, which only planted ____ trees.
(3) The total number of trees planted by the third-grade students is ____ trees.
(4) The total number of trees planted by class 4 is ____ times that of class 2.
(5) The average number of trees planted by the four classes is ____ trees.