📘 Class 8 · Mathematics

Chapter 7: Frequency Distribution Tables and Graphs

4 lessons

Frequency Distribution Tables and Graphs is where raw, unsorted data first gets organised — counted into a table, summarised with mean, median and mode, and shown visually as bar graphs, histograms and pie charts.

This is the first formal statistics chapter in the syllabus, and every later data chapter builds on it directly — Class 9's Statistics and Class 10's Statistics (grouped-data mean, mode, median, and ogive curves) are the same core ideas applied to larger, messier datasets.

1
Introduction — Central Tendency
Arithmetic mean, median and mode using the deviation method.
 2
Exercise 7.1 — Mean, Median and Mode
Problems based on mean, median and mode.
 3
Exercise 7.2 — Grouped Data
Organisation of grouped data and cumulative frequency.
 4
Exercise 7.3 — Graphs
Bar diagram, histogram, frequency polygon and frequency curve.

A subtle mix-up

Confusing frequency (how often a value occurs) with the value itself is a common error when calculating the mean by hand — a value of 5 occurring 3 times contributes 5×3=15 to the total, not just 5. Inconsistent interval widths when grouping data cause the second most common set of mistakes, since the graphs and averages built afterward assume every class covers the same span.