Along with an increase in population, electricity consumption per person is also increasing nationwide.
A survey is conducted for 560 families of Mangal Pande Nagar, Meerut. The following table gives the monthly consumption of electricity of these families.
Monthly consumption (in units) No. of families
0 - 100 160
100 - 200 120
200 - 300 180
300 - 400 60
400 - 500 40
Assuming that no family consumes more than 500 units of electricity, find :
(i) The mean monthly consumption.
(ii) The modal monthly class.
Measures of Central Tendency
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Question

Along with an increase in population, electricity consumption per person is also increasing nationwide.
A survey is conducted for 560 families of Mangal Pande Nagar, Meerut. The following table gives the monthly consumption of electricity of these families.
Monthly consumption (in units) No. of families
0 - 100 160
100 - 200 120
200 - 300 180
300 - 400 60
400 - 500 40
Assuming that no family consumes more than 500 units of electricity, find :
(i) The mean monthly consumption.
(ii) The modal monthly class.

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KnowledgeBoat · Accepted Answer

(i) Mean monthly consumption :

Monthly consumption (in units)	Class-mark (x)	No. of families (f)	fx
0 - 100	50	160	8000
100 - 200	150	120	18000
200 - 300	250	180	45000
300 - 400	350	60	21000
400 - 500	450	40	18000
Total		Σf = 560	Σfx = 110000

By formula,

Mean = $\dfrac{Σfx}{Σf} = \dfrac{110000}{560}$ = 196.43 (approx.).

Hence, the mean monthly consumption is 196.43 units (approx.).

(ii) The maximum frequency is 180, which corresponds to the class 200 - 300.

Hence, the modal monthly class is 200 - 300.