Answer:
It is not possible
Explanation:
First 6 people have 9 friends and since 6 people can have totally the same friends which could all be each other, we would have 5 friends(from same 6 people) + 4 friends(not from the 6). Therefore we would have total 9 people/students
In second group of 8 people, their friends could entirely be the same be the same as the first group's friends or they could all be each other's friend hence just an additional 8 students to the population
In the third group of 11 people/students, same thing could apply as above but total number of students would always surpass 25 with the additional population. Example 9+8+11= 28
Therefore it is not possible that 25 students would each have those number of friends.