\begin{tabular}{|c|c|c|}
\hline
\begin{tabular}{c}
[tex]$N^{\circ}$[/tex] de \\
caries
\end{tabular} & [tex]$f_i$[/tex] & [tex]$h_i$[/tex] \\
\hline
0 & 25 & 0.25 \\
\hline
1 & 20 & 0.20 \\
\hline
2 & [tex]$a$[/tex] & [tex]$c$[/tex] \\
\hline
3 & 15 & 0.15 \\
\hline
4 & [tex]$b$[/tex] & 0.05 \\
\hline
total & & \\
\hline
\end{tabular}



Answer :

Alright, let's solve this step-by-step.

### Step-by-Step Solution

1. Understanding the Given Data:
- The table represents the number of caries, the frequency ([tex]\( f_i \)[/tex]), and the relative frequency ([tex]\( h_i \)[/tex]).
- Let's rewrite the table with the missing values indicated:
[tex]\[ \begin{array}{|c|c|c|} \hline \text{Number of Caries} & f_i & h_i \\ \hline 0 & 25 & 0.25 \\ \hline 1 & 20 & 0.20 \\ \hline 2 & a & c \\ \hline 3 & 15 & 0.15 \\ \hline 4 & b & 0.05 \\ \hline \text{Total} & & \\ \hline \end{array} \][/tex]

2. Sum of Relative Frequencies:
- The sum of all relative frequencies should be 1.
- Given relative frequencies so far are:
[tex]\[ 0.25 + 0.20 + c + 0.15 + 0.05 = 1 \][/tex]
- Let's find [tex]\( c \)[/tex]:
[tex]\[ c = 1 - (0.25 + 0.20 + 0.15 + 0.05) = 1 - 0.65 = 0.35 \][/tex]

3. Total Sum of Frequencies:
- To find [tex]\( a \)[/tex] and [tex]\( b \)[/tex], we need to know the total sum of frequencies.
- Given frequencies so far are:
[tex]\[ 25 + 20 + a + 15 + b = \text{Total Frequency} \][/tex]
- Since [tex]\( h_i = \frac{f_i}{\text{Total Frequency}} \)[/tex]:
[tex]\[ 0.25 = \frac{25}{\text{Total Frequency}} \][/tex]
- Hence, Total Frequency = 100.

4. Calculate Missing Frequencies:
- Now, let's find [tex]\( f_i \)[/tex] for [tex]\( a \)[/tex] and [tex]\( b \)[/tex], knowing [tex]\( h_i \)[/tex]:
- For [tex]\( a \)[/tex]:
[tex]\[ h_i = 0.35 \implies a = h_i \times \text{Total Frequency} \implies a = 0.35 \times 100 = 35 \][/tex]
- For [tex]\( b \)[/tex]:
[tex]\[ h_i = 0.05 \implies b = h_i \times \text{Total Frequency} \implies b = 0.05 \times 100 = 5 \][/tex]

5. Assertion for Validation:
- Ensure:
[tex]\[ \text{Sum of frequencies} = 25 + 20 + 35 + 15 + 5 = 100 \][/tex]
- And:
[tex]\[ \text{Sum of relative frequencies} = 0.25 + 0.20 + 0.35 + 0.15 + 0.05 = 1 \][/tex]

Based on the above solution, the missing values are:

- [tex]\( a = 35 \)[/tex]
- [tex]\( b = 5 \)[/tex]
- Total Frequency = 100