The number of students in Class XI in Science, Arts and Commerce streams of a school over a period of 4 years (2011 - 2014) has been depicted through the bar chart given below. What is the average of the number of Arts students in the given class over the given period of 4 years?

20 30 35 32

30

Average number of Arts students = \(\frac{30 + 50 + 20 + 20 }{4}\) = \(\frac{120 }{4}\) = 30