Page 1: Introduction

Statistics deals with collection, organisation, analysis of data.

Measures of central tendency: mean, median, mode.

For grouped data: methods and graphical representation.

Page 2: Mean - Direct Method

x_i = class mark, f_i = frequency

Page 3: Mean - Assumed Mean Method

a = assumed mean (usually middle class mark)

Page 4: Mean - Step Deviation Method

h = class size (when uniform)

Page 5: Median

l = lower limit of median class
cf = cumulative frequency before median class
f = frequency of median class
N = Σf

Page 6: Mode

f_1 = modal class frequency
f_0 = previous, f_2 = next

Page 7: Cumulative Frequency Curve (Ogive)

Less than ogive: plot upper limit vs cumulative frequency

More than ogive: lower limit vs (N - cf)

Median from intersection at N/2

Page 8: Graphical Determination of Mode

From histogram: highest bar → modal class → mode formula

Page 9: Key Formulas Summary

• Three methods for mean
• Median formula
• Mode formula
• Ogive for median

Page 10: Practice Questions - Easy (1-10)

1. Class mark of 10-20.
2. Mean direct simple table.
3. Median class identification.
4. Modal class highest frequency.
5. Assumed mean choice.
6. Step deviation h.
7. Cumulative frequency meaning.
8. Ogive type.
9. N in median formula.
10. Mode from histogram.

Page 11: Practice Questions - Medium (11-20)

11. Mean using assumed mean.
12. Step deviation calculation.
13. Find median from frequency table.
14. Calculate mode grouped data.
15. Draw ogive description.
16. Find median graphically.
17. Mean of large data using step deviation.
18. Missing frequency if mean given.
19. Compare mean, median, mode.
20. Construct frequency table from data.

Page 12: Practice Questions - Hard (21-30)

21. Two missing frequencies from mean.
22. Ogive intersection for median.
23. Large table all three measures.
24. Unequal class interval adjustment.
25. Mode from ogive hint.
26. Real data analysis.
27. Board level frequency table.
28. Graphical mode determination.
29. Combined mean of groups.
30. Advanced missing frequency.

Page 13: Methods Comparison Table

Direct, assumed, step deviation.

Page 14: Common Mistakes

• Wrong class mark
• Cumulative frequency error
• Forgetting h in median/mode
• Wrong modal class
• Sign error in deviation

Page 15: Previous Year Questions

Mean from table, median/mode, ogive.

Page 16: Exam Tips

• Show frequency table clearly
• Write formula first
• Draw neat ogive
• Choose best mean method
• Check N/2 for median

Page 17: Quick Revision Sheet

All formulas, steps.

Page 18: Final Motivation

Chapter 14 complete! Statistics is scoring with practice.

Only Probability left.

Class 10 Maths almost done 🦖

Page 19: Extra Numericals

More solved tables.

Page 20: Ogive Drawing

Step-by-step.

Page 21: Mean Method Choice

When to use which.

Page 22: Mode Formula Explanation

Why it works.

Page 23: Board Pattern

Frequency table + mean/median/mode.

Page 24: Extra Practice

More questions.

Page 25: Missing Frequency

Common type.

Page 26: Graphical Median

Ogive intersection.