The Following Table Gives the Frequency Distribution of Trees Planted by Different Housing Societies in a Particular Locality - Algebra

The following table gives the frequency distribution of trees planted by different Housing Societies in a particular locality:

 No. of Trees No. of Housing Societies 10-15 2 15-20 7 20-25 9 25-30 8 30-35 6 35-40 4

Find the mean number of trees planted by Housing Societies by using ‘Assumed Means Method’

Solution

By Assumed Mean Method

 No. of trees Class mark                 xi di=xi-A No of housing             societies(fi) fidi 10-15 12.5 -10 2 -20 15-20 17.5 -5 7 -35 20-25 22.5toA 0 9 0 25-30 27.5 5 8 40 30-35 32.5 10 6 60 35-40 37.5 15 4 60 Total - -  sumf_i=36 sumf_id_i=105

bar d=(sumf_id_i)/(sumf_i)=105/36=2.916

Mean = bar x=A+bard = 22.5 + 2.916 = 25.42

Therefore the mean number of trees planted by Housing Societies is 25.42.

Concept: Mean of Grouped Data
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