In the set of natural numbers 1 to 52, what percentage are multiples of 5, to one decimal place?

1. The set is $S=\{1,2,3,\dots,52\}$, so $n(S)=52$. 2. The multiples of 5 in it are $\{5,10,15,20,25,30,35,40,45,50\}$, so $n(E)=10$. 3. Apply $\%n(E)=\dfrac{n(E)}{n(S)}\times100\%$. 4. That gives $\dfrac{10}{52}\times100\%=19.2307\%$. 5. Rounded to one decimal place the answer is $19.2\%$. Answering $20.0\%$ assumes 10 out of 50 rather than 52. _Source: NECTA CSEE 2022 Basic Mathematics 041, Question 1: Numbers, Fractions, Percentages and Logarithms_