To determine the class interval of the given data, we follow these steps:
1. First, identify the range for each age group. For example, the first group is "40 up to 50," which ranges from 40 to 49, covering 10 values.
2. Verify the range for each interval:
- 40 to 49: This interval spans from the beginning of 40 to just before 50, which covers 10 units (40, 41, 42, ..., 49).
- 50 to 59: This interval spans from the beginning of 50 to just before 60, which also covers 10 units (50, 51, 52, ..., 59).
- 60 to 69: This interval spans from the beginning of 60 to just before 70, again covering 10 units (60, 61, 62, ..., 69).
3. We observe that each age group interval consistently covers 10 units.
Thus, the class interval for the given age groups is:
[tex]\[ \boxed{10} \][/tex]
So, the correct answer is [tex]\( 10 \)[/tex].
