Correct option is C

​Given:
Year-wise number of girls in College A:
2018: 720, 2019: 840, 2020: 1380, 2021: 1920, 2022: 2580, 2023: 2880
Formula Used:
​$$\text{Average} = \frac{\text{Sum of all values}}{\text{Number of values}}$$​​

Solution:
Total number of girls in College A over the six years.
720 + 840 + 1380 + 1920 + 2580 + 2880 = 10320
Average = $$\frac{10320}{6} = 1720$$​

Correct option is A

Given:
Number of boys in College D in 2020 = 1280
Number of boys in College D in 2021 = 1060
Formula Used:
$$\text{Percentage Decrease} = \left( \frac{\text{Previous Value} - \text{Current Value}}{\text{Previous Value}} \right) \times 100$$​​
Solution:
​$$\text{Percentage Decrease} = \left( \frac{1280 - 1060}{1280} \right) \times 100 = 17.185 \approx 17\%$$​​

Correct option is C

Given:
2018: Boys = 1300, Girls = 1320
2019: Boys = 1100, Girls = 720
2020: Boys = 540, Girls = 480
2021: Boys = 1080, Girls = 1140
2022: Boys = 1360, Girls = 1300
2023: Boys = 2160, Girls = 2540
Formula Used:
Total Students = Boys + Girls
Solution:
2018: Total Students = 1300 + 1320 = 2620
2019: Total Students = 1100 + 720 = 1820
2020: Total Students = 540 + 480 = 1020
2021: Total Students = 1080 + 1140 = 2220
2022: Total Students = 1360 + 1300 = 2660
2023: Total Students = 2160 + 2540 = 4700
Therefore, the total number of students in College E exceeds 2600 for exactly 3 years: 2018, 2022, and 2023.

Correct option is D

Given:

Boys in College E in 2019 = 1100, Girls in College E in 2019= 720
Number of girls in College B in 2022 = 1180
​Formula Used:
​$$\text{Percentage Increase} = \left( \frac{\text{Total Students in College E in 2019} - \text{Girls in College B in 2022}}{\text{Girls in College B in 2022}} \right) \times 100$$​
​Solution:​​
Total students in College E in 2019 = 1100 + 720 = 1820
Percentage Increase = $$\left( \frac{1820 - 1180}{1180} \right) \times 100 = 54.2 \approx 54\%$$​​​

Correct option is B

​Given:
Number of boys in 2023: A (2460) , B (1960) , C = 2340, D = 2440, E = 2160
Formula Used:
​$$\text{Average} = \frac{\text{Sum of all values}}{\text{Number of values}}$$​​

Solution:
Total Number of boys in the year 2023 in all the five colleges taken together =  2460 +1960+2340+2440+2160 = 11360
Average = $$\frac{11360}{5}= 2272$$​​