What is the difference between 10% and $\frac{1}{10}$

Question

In a national competition , ech school had to choose 10% of students who participated in the competition .

So my question is , why they didn't asked for $\frac{1}{10}$ of students who participated ?

For example for 200 students we have to choose 20 students ! For 120 we have to choose 12 . But for 20 we have to choose 2 or 10 because if we choose 2 we are doing the $\frac{1}{10}$ case ! So if number of students is small than 100 we have to choose in all cases 10 students ???

Answer 1

I define $\%=\frac{1}{100}$ so

$$10\%=10\cdot\frac{1}{100}=\frac{1}{10}.$$

Answer 2

To take $10\%$ of a quantity $X$, you multiply $X$ by $\frac{1}{10}$. So, for example, $10\%$ of $20$ is $\frac{1}{10}\cdot 20 = 2$.

Answer 3

If a school has to send ${1\over10}$ of its students then strictly speaking that school cannot take part if its total number of students is not divisible by $10$. If the school has to send $10\%$ of its students then everyone accepts that the resulting number is rounded to the nearest integer.