Let the population at the beginning of the first year be P.
At the end of the first year, the population increases by 5%, so it becomes:
\[ P \times 1.05 \]
At the end of the second year, the population again increases by 5%, so it becomes:
\[ P \times 1.05 \times 1.05 = P \times 1.05^2 \]
We are given that the population at the end of the second year is 9975:
\[ P \times 1.05^2 = 9975 \]
\[ P = \frac{9975}{1.1025} = 10000 \]
Thus, the population size at the beginning of the first year is 10,000.
In a survey, 60 % of 200 students prefer online classes, and 25 % of the remaining prefer hybrid classes. How many students prefer neither?