Modal class
- CBSE · NCERT Class 10, Ch 13 Statistics
The modal class is the class interval with the highest frequency in grouped data, and the mode lies inside it.
The mode is the value that turns up most. In grouped data, you first find the class with the biggest frequency. That is the modal class. A formula then places the mode inside it:
- Mode = l + ((f₁ − f₀) ÷ (2f₁ − f₀ − f₂)) × h.
- l is the lower limit of the modal class, and h is the class size.
- f₁ is the modal class's frequency. f₀ and f₂ are the frequencies of the classes just before and just after it.
A small example
Classes 0-10, 10-20 and 20-30 have frequencies 4, 9 and 6. The modal class is 10-20. So l = 10, h = 10, f₁ = 9, f₀ = 4 and f₂ = 6. The mode is 10 + (5 ÷ 8) × 10 = 16.25.
Where marks go
Question 38 of CBSE's 2026-27 Maths Standard sample paper asks, in part (i), for the most common class. That alone is 1 mark. Part (iii)(B) asks for the mode, for 2 marks. The 2026-27 Maths Standard marking scheme gives half a mark for naming the modal class with l, f₀, f₁ and f₂.
The formula with the numbers put in earns 1 mark. The answer, 37.5, earns the last half. Under step marking, each value written down can earn its early mark. The median class is found a different way, so keep the two apart.
Sources
Facts last checked against these sources on 30 September 2026.
- NCERT Mathematics, Class X, Chapter 13: Statistics (reprint 2026-27) - section 13.3 · NCERT
- Mathematics Standard (041) Marking Scheme, Class X 2026-27 - Question 38(i) and (iii)(B) · CBSE Academic Unit
- Mathematics Standard (041) Sample Question Paper, Class X 2026-27 - Question 38 · CBSE Academic Unit
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