Question

find the mean age of 100 residents of a colony from the following data:age in year 0 10,10 20,20 30,30 40,40 50,50 60,60 70 and no of persons 10,15,25,25,10,10,5​

Answer 1

Soln:

Class interval Frequency Cumulative frequency

0 – 10                        5                           5

10 – 20                      25                       30 (F)

20 – 30                         x (f)                  30 + x

30 – 40                          18                     48 + x

40 – 50                           7                         55 + x

N = 170  

 

Given

Median = 24

Then, median class = 20 – 30

L = 20,   h = 30 -20 = 10, f = x,      F = 30

Median = L+N2−Ff×h

24 = 20+55+x2−30x×10

24 – 20 = 55+x2−30x×10

4x = (55+x2−30)×10

4x = 275 + 5x – 300

4x – 5x = -25

-x = -25

x = 25

Missing frequency = 25

Answer 2

Answer:

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