To solve the first question in the image:

1. Panjang interval kelas pada tabel distribusi frekuensi di atas (Class interval length):

The interval length is calculated by subtracting the lower bound of a class from the upper bound.

For example, for the first class interval (40–49), the length is: $49 - 40 + 1 = 10$

Therefore, the correct answer is e. 10.

Would you like more details or have further questions? Here are some related questions:

1. What is the purpose of class intervals in frequency distribution?
2. How do we calculate the midpoint of a class interval?
3. How do you construct a frequency distribution table?
4. What is cumulative frequency, and how is it useful?
5. How do you calculate the relative frequency of each class?

Tip: Always check whether class intervals are continuous; sometimes you may need to adjust intervals to calculate the frequency correctly.