Statistics PYQs
Practise grouped-data calculations, missing frequencies, and board-style statistics questions.
Revise how to calculate mean, median, and mode from grouped data, including the correct class intervals, cumulative frequencies, and formula values. Use the topic links to practise missing-frequency problems and explain each answer with accurate working.
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CBSE Board Exam Blueprint & Topic Weightage: Statistics
In the Class 10 CBSE Board Examination, Statistics is a high-yielding component of Unit 7: Statistics & Probability, consistently carrying 7 to 8 marks in the annual 80-mark written board paper. Recurring question formats observed over past board papers include:
- Section A (1 Mark MCQ): Empirical relationship between three measures of central tendency: \(\text{Mode} = 3\text{Median} - 2\text{Mean}\), class mark calculation \(\frac{\text{upper}+\text{lower}}{2}\), and modal class identification.
- Section C (3 Marks): Calculating Mean of grouped data using Direct Method or Assumed Mean Method, and calculating Mode using modal formula \(l + (\frac{f_1-f_0}{2f_1-f_0-f_2})h\).
- Section D (5 Marks): Calculating Median of grouped data using \(l + (\frac{N/2 - cf}{f})h\), and solving for missing frequencies \(x\) and \(y\) (or \(f_1, f_2\)) when total frequency and median are given.
Key Revision Tips & Common Pitfalls
In median calculations, the cumulative frequency \(cf\) in the formula is the cumulative frequency of the class PRECEDING the median class. For continuous grouped data, ensure classes are exclusive (if given 0-9, 10-19, convert to 0.5-9.5, 9.5-19.5 before taking boundaries). Always verify that calculated mean/median/mode lies within the modal or median class interval.