Draw a frequency polygon and frequency curve for the following data on landholdings of farmers .

Area in hectares 11-20 21-30 31-40 41-50 51-60 61-70 71-80

No. of farmers 58 103 208 392 112 34 12

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Solution

Here, the given data is in discontinuous form. So, we have to convert it into continuous form.

This can be done by extending the classes by half of the gap between two consecutive classes.
We take the imagined classes 0.5-10.5 and 80.5-90.5 with zero frequency .

Extended class interval Class mark Frequency

0.5-10.5 5.5 0

10.5-20.5 15.5 58

20.5-30.5 25.5 103

30.5-40.5 35.5 208

40.5-50.5 45.5 392

50.5-60.5 55.5 112

60.5-70.5 65.5 34

70.5-80.5 75.5 12

80.5-90.5 85.5 0

The frequency polygon is shown below.

The frequency curve is shown below:

Suggest Corrections

Class interval	1−10	11−20	21−30	31−40	41−50	51−60
Frequency	8	3	6	12	2	7

Age	20−30	30−40	40−50	50−60	60−70	70−80	80−90
Frequency	3	61	132	153	140	51	2

Marks Obtained	0−10	10−20	20−30	30−40	40−50	50−60	60−70	70−80
Number of Students	10	16	20	20	22	15	8	5

Area in hectares	11-20	21-30	31-40	41-50	51-60	61-70	71-80
No. of farmers	58	103	208	392	112	34	12

Time required (in minutes )	31-40	41-50	51-60	61-70	71-80	81-90
No. of customers	12	18	27	20	17	6

Weight (in mg)	11-20	21-30	31-40	41-50	51-60
No. of seeds	18	22	30	16	4