To solve this question, we need to find the relative frequency for the class with a lower class limit of 15, which corresponds to the age group 15-18. The number of students in this group is 2.

Steps:

1. Total number of students: First, calculate the total number of students by summing all the frequencies. $2 + 7 + 5 + 9 + 3 + 2 = 28$

2. Relative frequency formula: The relative frequency is calculated using the formula: $\text{Relative Frequency} = \left( \frac{\text{Frequency of the class}}{\text{Total number of students}} \right) \times 100$ For the class 15-18: $\text{Relative Frequency} = \left( \frac{2}{28} \right) \times 100 = 7.14\%$

Final Answer:

The relative frequency for the class with a lower class limit of 15 is 7.1% (rounded to one decimal place).

Would you like further details on this process or have any questions?

Here are 5 related questions you might want to consider:

1. How do you calculate cumulative frequency?
2. What is the difference between relative and absolute frequency?
3. How is frequency distribution used in statistics?
4. Can you explain how to calculate the mean from a frequency table?
5. How would you graph a frequency distribution?

Tip: Always ensure that the total frequency is correct before calculating relative frequency to avoid errors in percentages.