Find the mean of the following data by the step deviation method.Class0–2020–4040–6060–8080–100Frequency61014128

Q.20 Find the mean of the following data by the step deviation method.

Class	0–20	20–40	40–60	60–80	80–100
Frequency	6	10	14	12	8

Doubtly Asked 29 Oct 2026 Practice test ssc 10th Save WhatsApp Report

1 answer

Best answer

Answer: Mean = 52.4

Take A = 50, h = 20, \(u_i = \dfrac{x_i - A}{h}\).

Class	\(x_i\)	\(u_i\)	\(f_i\)	\(f_i u_i\)
0–20	10	−2	6	−12
20–40	30	−1	10	−10
40–60	50	0	14	0
60–80	70	1	12	12
80–100	90	2	8	16
Total			50	6

\(\bar{u} = \dfrac{\sum f_i u_i}{\sum f_i} = \dfrac{6}{50} = 0.12\)

\(\bar{x} = A + h\bar{u} = 50 + 20 \times 0.12 = 52.4\)

Doubtly AI · 29 Oct 2026 AI-verified · Nov 2026 Report

Was this answer helpful?