Chapter 14: Statistics

Statistics closes the Class 10 syllabus by finding the mean, mode and median of grouped data — direct, assumed-mean and step-deviation methods for the mean, dedicated formulas for mode and median built from a cumulative frequency column — and representing that same cumulative frequency graphically with ogive curves.

Misidentifying the modal or median class from the frequency table throws off every step that follows it, and inclusive class intervals (like 10–19, 20–29) need converting to continuous boundaries before any formula here can be applied correctly. Where a "less than" ogive and a "more than" ogive cross on the same graph is itself the median — a fully graphical route to the same answer the formula gives.