Page 1 - Lesson Note MCT 2 54
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SAI INTERNATIONAL SCHOOL
ECONOMICS
Class-XI
CHAPTER 9
Measures of Central Tendency – Median and Mode
(Lesson Note - 54)
TOPICS TO BE COVERED-
- calculate median in special cases of continuous series.
-Problems on inclusive series.
-Problems on open-end series.
-Problems on un-equal class interval and problems on missing frequency.
Ex. Calculation of median from the following figures.
Class interval 10 - 19 20 - 29 30 - 39 40 -49 50 - 59 60- 69
Frequencies 12 19 20 21 15 13
Answer: - calculation of median.
Inclusive series Exclusive series Frequency Cumulative
(X) (F) frequency (C.F)
10 – 19 9.5 – 19.5 12 12
20 – 29 19.5 – 29.5 19 31
30 - 39 29.5 – 39.5 20 51
40 - 49 39.5 – 49.5 21 72
50 - 59 49.5 – 59.5 15 87
60 - 69 59.5 –69.5 13 100
= ∑ = 100
Median = ℎ ℎ
2
100
= = 50th data in the series.
2
Median class is 29.5 – 39.5
= 29.5, f = 20, c. f = 31, i = 10.
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