First of all, it is impossible for the yellow hat students to raise their hands. He can see a red hat classmate, but the other person doesn't raise his hand. He can't conclude that he is wearing a red hat.

The remaining problem is the psychological logic reasoning of Red Hat students.

Let's simplify the problem first, because 25:75= 1:3, 1+3=4.

The simplest case is 4 students, 1 red 3 yellow.

At this time, when the teacher asks questions for the first time, Red Hat students will raise their hands, because all three students he sees are yellow hats (the time is 0 minutes).

Look at 2 red and 6 yellow.

The first time no one raised his hand, red hat A saw 1, red and yellow, and red hat B didn't raise his hand. Party A immediately knew that he was also a red hat, and vice versa, so he asked a second question and two people raised their hands at the same time (the time was 1 minute).

Look at the situation of San Hong Jiu Huang. Red A, red B and red C can all see two red hats. Every time the teacher asks questions, they wonder why the other two red hats don't raise their hands. Every time the teacher asks a question, he rules out an uncertainty. From the 0 th minute to the 0 th minute, none of them will raise their hands. In the second minute, three people will raise their hands at the same time.

.......

Conclusion: In 24 minutes, 25 red hats raised their hands at the same time.