Question

Calculate arithmetic mean for the following data by short cut method

Class interval 10-20 20-30 30-40 40-50 50-60 60-70 70-80

Frequency 5 10 15 20 25 18 7
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Answer 1

Answer :

48.2

Explanation

Class interval 10-20 20-30 30-40 40-50 50-60 60-70 70-80

Class mark = upper limit + lower limit /2

For example =10+20/2=15

Xi= 15, 25, 35, 45, 55, 65, 75

Fi = 5, 10, 15, 20, 25, 18, 7

XiFi=(15*5) (25*10) (35*15) (45*20)

(55*25) (65*18) (75*7)

XiFi=75, 250, 525, 900, 1375, 1170, 525

Airthmatic mean=∑fixi/∑f

Fixi= 4820

fi=100

Airthmatic mean=∑fixi/∑f

4820/100

48.2