If the median of the distribution is given below is 28.5, find the values of x and y.

Class interval

Frequency

0 − 10

5

10 − 20

x

20 − 30

20

30 − 40

15

40 − 50

y

50 − 60

5

Total

60

The cumulative frequency for the given data is calculated as follows.

Class interval

Frequency

Cumulative frequency

0 − 10

5

5

10 − 20

x

5+ x

20 − 30

20

25 + x

30 − 40

15

40 + x

40 − 50

y

40+ x + y

50 − 60

5

45 + x + y

Total (n)

60

From the table, it can be observed that n = 60

45 + x + y = 60

x + y = 15 (1)

Median of the data is given as 28.5 which lies in interval 20 − 30.

Therefore, median class = 20 − 30

Lower limit (l) of median class = 20

Cumulative frequency (cf) of class preceding the median class = 5 + x

Frequency (f) of median class = 20

Class size (h) = 10

From equation (1),

8 + y = 15

y = 7

Hence, the values of x and y are 8 and 7 respectively.

  • 145
What are you looking for?