Question

Class marks in a grouped frequency table are useful to find:

Options

• Mean

• Median

• Mode

• All of these

Answer 1

Mean

Explanation:

Class Mark (x_i): This is the midpoint or central value of a class interval, calculated as:

Class Mark = `("Lower Limit" + "Upper Limit")/2`

Finding the Mean: When calculating the mean `(barx)` for grouped data, we assume that the frequency of each class is centered around its midpoint. The direct formula explicitly uses the class marks (x_i):

`bar(x) = (sumf_ix_i)/(sumf_i)`

Median and Mode: Calculating the median and mode of grouped data relies on class boundaries, cumulative frequencies or individual class frequencies, rather than the class marks.