In a retail market, fruit vendor were-selling mangoes kept in packing boxes. These boxes contained varying number of mangoes. The following was the distribution of mangoes according to the number of boxes.


Number of mangoes:



50-52



53-55



56-58



59-61



62-64



Number of boxes:



15



110



135



115



25



Find the mean number of mangoes kept in a packing box. Which method of finding the mean did you choose?


Number of mangoes



Number of boxes (fi)



50-52



15



53-55



110



56-58



135



59-61



115



62-64



25



We may observe that the class intervals are not continuous. There is a gap between two class intervals so we have to add from lower class limit of each interval.


Class size (h) of this data = 3


Now taking 57 as assumed mean, we can calculate as follows:


Class interval



fi



xi



di = xi - 57



ui =



fiui



49.5-52.5



15



51



-6



-2



-30



52.5-55.5



110



54



-3



-1



-110



55.5-58.5



135



57



0



0



0



58.5-61.5



115



60



6



1



115



61.5-64.5



25



63



3



2



50




N = 400






∑fiui = 25



Mean = A + * h


= 57 + * 3


= 57 +


= 57 + 0.1875 = 57.1875


= 57.19


Number of mangoes kept in packing box is 57.19


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