Mathematics · JEE | STATISTICS

In the formula for the assumed mean method \( \bar{x} = a + \frac{\sum f_i d_i}{\sum f_i} \), what does \( f_i \) represent?

1. A
   Class mark of the \( i \)-th class
2. B
   Deviation of the \( i \)-th class
3. C
   Class size of the \( i \)-th class
4. D
   Frequency of the \( i \)-th class interval