Q2 of 11 Page 69

The following table shows the electricity (in units) used by 25 families of Eklara village in a month of May. Complete the table and answer the following questions.


(1) How many families use 45 units electricity?


(2) State the score, the frequency of which is 5.


(3) Find N and Σ fixi


(4) Find the mean of electricity used by each family in the month of May.


From the given table it can be seen that 7 number of families consumed 30 units of electricity, 2 families consumed 45 units of electricity, similarly, 8,5 and 3 number of families consumed 60, 75, and 90 units of electricity respectively.


Further moving on to the questions,


(1) 2, because in the table provided, xi= 45, f is 2.


(2) 75, because in the table provided xi for fi = 5 is 75.


(3) From the table,


N = Σ fi


= 7 + 2 + 8 + 5 + 3


= 25.


Σ fixi= 210+90+480+375+270


= 1425.


(4) From the table,


Σ fi xi = 1425


Σ fi = 25


Formula


Where, xi = score ; fi = frequency ; N = total frequency


∴ Mean


= 1425/25


= 57.


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