To find the joint relative frequency of elementary age students who prefer winter, you first need to determine the frequency of elementary age students who prefer winter and then divide it by the total number of students surveyed.
From the table:
- The number of elementary age students who prefer winter is 84.
- The total number of students surveyed is 251.
Now, calculate the joint relative frequency:
\[ \text{Joint relative frequency} = \frac{\text{Number of elementary students who prefer winter}}{\text{Total number of students}} = \frac{84}{251} \]
Now perform the calculation:
\[ \frac{84}{251} \approx 0.3343 \]
To convert this to a percentage, multiply by 100:
\[ 0.3343 \times 100 \approx 33.43 \]
Rounding to the nearest whole number, the joint relative frequency of elementary age students who prefer winter is:
\[ \boxed{33} \text{ percent} \]