The given bar graph represents the number of students who appeared in the board examination in session 2017 - 18 and 2018-19. Study the graph and answer the question that follows. The difference between the average number of students of Science and Mathematics streams in 2017-2018 and that in Commerce and Vocational in 2018-19 is:?

Option 3 : 4

Given 

From the graph, 

No of science student in 2017 - 2018 = 25

No of Mathematics student in 2017 - 2018 = 53

No of commerce student in 2018 - 2019 = 48

No of Vocational student in 2018 - 2019 =  38

Formula Used 

Average = sum of observation/No. of observation

Calculation

⇒ Sum of no. of science and Mathematics student in 2017 - 2018 = 25 + 53 = 78

⇒ Sum of no. of commerce and vocational student in 2018 - 2019 = 48 + 38 = 86

⇒ Difference = 86 - 78 = 8 

⇒ Average = 8/2 = 4 

∴ the difference between the average no. of student is 4