what do u mean by mode,mean,median …

Median

Median refers to the value which lies in the middle of the data when data is arranged in an increasing or decreasing order. Half of the observations lie above the median and the other half below it.

To calculate the median, the data is first arranged in an ascending or descending order. Then the middle value is observed.

For eg; 2, 4, 6, 8, 9

6 is the median in this case since it lies in the middle. There are two observations above and below 6.

In case of odd number of observation, the value of median is one of the observations in the existing data.

In case of odd number of observation, the value of median is one of the observations in the existing data.

In case of even number of observations, the value of median is not one of the observations in the existing data.

For eg : 2,4,6,8,9,10

The median is the average of two middle numbers 6 and 8.

Median = 6+8/2

Median =10/2=5

Problem : The scores in mathematics test (out of 25) of 15 students is as follows:

19, 25, 23, 20, 9, 20, 15, 10, 5, 16, 25, 20, 24, 12, 20

Find the mean of this data.

Solution:

The data is first arranged in an ascending order. We get :

5,9,10,12,15,16,19,20,20,20,20,23,24,25,25

It can be seen from this arrangement that 20 at the eight place is in the middle of the data. There are 7 observations below 20 and 7 observations above 20.

Therefore, 20 is the median of the data.