NCERT Solutions for Class 10 Maths Chapter 13 Statistics

Short Note:

• Direct Method: Mean = Σf_ix_i / Σf_i, where x_i are class marks and f_i are frequencies.

• Assumed Mean Method: Mean = a + (Σf_id_i / Σf_i), where d_i = x_i − a (a = assumed mean).

• Step-Deviation Method: Mean = a + [(Σf_iu_i / Σf_i) × h], where u_i = (x_i−a)/h.

Short Note:

• Mode = l + [(f₁−f₀) / (2f₁−f₀−f₂)] × h, where l = lower limit of modal class, f₁ = frequency of modal class, f₀ = frequency of class preceding it, f₂ = frequency of class succeeding it, h = class width.

Short Note:

• Median = l + [(n/2 − cf) / f] × h, where l = lower limit of median class, n = total frequency, cf = cumulative frequency of class preceding median class, f = frequency of median class, h = class width.

Short Note:

• A cumulative frequency curve (ogive) can be drawn as 'less than' type or 'more than' type; the x-coordinate of the intersection of both ogives gives the median of the data.