​The table given shows me total number of students of a college and the number of girls who are studying in four different courses — Data science. Cloud computing. Statistics and Image processing in 3 different years. 

Year/Courses	2016		2017		2018
	Total number of students	Total number of girls	Total number of students	Total number of girls	Total number of students	Total number of girls
Data science	800	500	900	450	760	400
Cloud computing	1600	400	1800	1000	1500	700
Statistic	1400	600	1500	700	1040	400
Image processing	1200	600	1300	600	800	200

​What is the average number of boys studying in all the four courses in the year 2017?

Correct option is B

Concept Used:

Number of boys = Total students - Total girls

​$$\text{Average number of boys} = \frac{\text{Total boys}}{\text{no of course}}$$​​

Solution:

The number of boys for each course

1. Data Science (2017)

Total students = 900 , Total girls = 450

Number of boys = 900 - 450 = 450

2. Cloud Computing (2017)

Total students = 1800 , Total girls = 1000

Number of boys = 1800 - 1000 = 800

3. Statistics (2017)

Total students = 1500 , Total girls = 700

Number of boys = 1500 - 700 = 800

4. Image Processing (2017)

Total students = 1300 , Total girls = 600

Number of boys = 1300 - 600 = 700 

Now, 

Total boys = 450 + 800 + 800 + 700 = 2750  

​$$\text{Average number of boys} = \frac{2750}{4} = 687.5$$ 

The average number of boys studying in all four courses in the year 2017 is 687.5.