4. In one primary school on Friday, the heights of all present students in one 7th grade class were measured. It was found that their average height is $164 \mathrm{~cm}$. That day, two students, Maja and Paula, were absent from class. Maja is $160 \mathrm{~cm}$ tall, and Paula is $162 \mathrm{~cm}$ tall. If their heights are also taken into account, the average height of all students in that class is $163.8 \mathrm{~cm}$. Determine the total number of students in that class.
4. Let $n$ be the number of students whose height was measured on that Friday.

Their total height is $164 \mathrm{ncm}$.

$1 \mathrm{POINT}$

If we add to this total height the sum of the heights of Maja and Paula (322 cm),

the total height of all $n+2$ students in that classroom will be $163.8 \cdot(n+2)$. 2 POINTS

The equation $164 n+322=163.8 \cdot(n+2)$ holds. 1 POINT

By solving it, we get $n=28$. 1 POINT

In that classroom, there are a total of $n+2=30$ students. 1 POINT

TOTAL 6 POINTS