Explanation:

As per the give table,
Total number of student in the college A$$=\dfrac{25\times 8000}{100}=2000$$
Total number of student in the college B$$=\dfrac{35\times 10000}{100}=3500$$
Total number of student in the college C$$=\dfrac{45\times 15000}{100}=6750$$
Total number of student in the college D$$=\dfrac{28\times 9000}{100}=2520$$
Total number of student in the college A$$=\dfrac{35\times 11000}{100}=3850$$
Hence average number of students are studying in all the colleges$$=\dfrac{2000+3500+6750+2520+3850}{5}=3724$$