A survey was conducted by a group of students as a part of their environment awareness program, in which they collected the following data regarding the number of plants in 20 houses in a locality. Find the mean number of plants per house


Number of plants



0 - 2



2 – 4



4 - 6



6 - 8



8 - 10



10 - 12



12 -14



Number of houses



1



2



1



5



6



2



3



Which method did you use for finding the mean, and why?

The above given data can be represented in the form of table as below:


Class Interval



fi



xi



fixi



0-2



1



1



1



2-4



2



3



6



4-6



1



5



5



6-8



5



7



35



8-10



6



9



54



10-12



2



11



22



12-14



3



13



39




∑fi = 20




∑fixi = 162



Mean can be calculated as follows:




= 8.1


We will use the direct method in this as the values of xi and fi are small.


13