1. Vitya Pereperepkin always calculates percentages incorrectly in surveys: he divides the number of people who answered in a certain way by the number of all the others. For example, in the survey "What is your name?", conducted among 7 Anyas, 9 Ols, 8 Yuls, Vitya counted $50 \%$ Yuls.

Vitya conducted a survey in his school: what kind of triangle is one with sides $3,4,5$? According to his calculations, $5 \%$ answered "acute-angled", $5 \%$ - "obtuse-angled", $5 \%$ - "such a triangle does not exist", $50 \%$ - "right-angled", and the remaining $a \%$ - "it depends on the geometry". What is $a$?
Answer: $a=110$ (in the $2-nd$ variant $a=104$). When Vitya calculates that some part of the students constitutes $5 \%$ of the entire class, in reality, it constitutes $5 / 100=1 / 20$ of the remaining students, $1 / 21$ of the entire class. Similarly, Vitya's $50 \%$ is one third of the class. Therefore, all those who answered in the first four ways constitute a share of $1 / 21+1 / 21+1 / 21+1 / 3=10 / 21$ of the entire class. Thus, the remaining students constitute $11 / 10$ of all except them, that is, according to Vitya's opinion, $110 \%$.