A survey conducted on 20 households in a locality by a group of students resulted in the following frequency table for the number of family members in a household.

Step 1: Recall the mode formula for the grouped data
Mode = l + \frac{f_1 - f_0}{2f_1 - f_0 - f_2} * h
Where,
l - The lower boundary of the modal class,
h - The class size,
f_1 - The frequency of modal class,
f_0 - The frequency of the class preceding the modal class,
f_2 - The frequency of the class succeeding the modal class.
Step 2: Identify the modal class and locate the values of the frequencies.
NOTE: Locate a class with the maximum frequency, called the modal class.
(The mode is a value inside the modal class)
Here the maximum class frequency is 8, and the class corresponding to this
frequency is 3-5.
So, the modal class is 3-5.
lower boundary l = 3
Class size h = 5 - 3 = 2
The frequency of modal class f_1 = 8
The frequency of the class preceding the modal class f_0 = 7
The frequency of the class succeeding the modal class. f_2 = 2
Step 3: Substitute the values in the formula and calculate the mode.
Mode = l + \frac{f_1 - f_0}{2f_1 - f_0 - f_2} * h
= 3 + \frac{8 - 7}{2*8 - 7 - 2} * 2
= 3 + \frac{1}{7} * 2
= 3 + 0.2857
= 3.286
Hence, mode = 3.286