Q2 of 37 Page 14

Write the median class of the following distribution: [CBSE 2009]


Class

0 - 10

10 - 20

20 - 30

30 - 40

40 - 50

50 - 60

60 - 70

Frequency

4

4

8

10

12

8

4

To find median class,

Assume Σfi = N = Sum of frequencies,


fi = frequency


and Cf = cumulative frequency


Lets form a table.



AGE(years)

NUMBER OF PATIENTS(fi)

Cf

0 - 10

4

4

10 - 20

4

4 + 4 = 8

20 - 30

8

8 + 8 = 16

30 - 40

10

16 + 10 = 26

40 - 50

12

26 + 12 = 38

50 - 60

8

38 + 8 = 46

60 - 70

4

46 + 4 = 50

TOTAL

50

  

So, N = 50


⇒ N/2 = 50/2 = 25


The cumulative frequency just greater than (N/2 = ) 25 is 26, so the corresponding median class is 30 - 40.


Hence, median class = 30 - 40

More from this chapter

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1

Find the class marks of classes 10 - 25 and 35 - 55. [CBSE 2008]

 3

What is the lower limit of the modal class of the following frequency distribution?[CBSE 2009]


Age (in years)

0 - 10

10 - 20

20 - 30

30 - 40

40 - 50

50 - 60

60 Number of patients

16

13

6

11

27

18
4

If the mean of 5 observations x, x + 2, x + 4, x + 6 and x + 8 is 11, find the value of x.[CBSE 2014]

 5

If the mean of 25 observations is 27 and each observation is decreased by 7, what will be the new mean?[CBSE 2014]