Frequency density of a class is the ratio of:

The correct answer is (b).

Frequency density is the number of observations per unit of the class interval. It is calculated by dividing the class frequency by the class interval.

For example, if a class has a frequency of 10 and a class interval of 5, the frequency density is 2.

(a) The class frequency to the total frequency is the proportion of observations in a class to the total number of observations.

(c) The class interval to the class frequency is the width of a class interval divided by the number of observations in that class.

(d) None of these is the correct answer.