Q3 of 43 Page 289

Find the median from following frequency distribution:





















Class



0-100



100-200



200-300



300-400



400-500



500-600



Frequency



64



62



84



72



66



52



Here, we have grouped data given in the table. We need to find cumulative frequency of the data, which will predict our answer.

So,












































CLASS



FREQUENCY


(f)



CUMULATIVE FREQUENCY


(cf)



0 – 100



64



64



100 – 200



62



64 + 62 = 126



200 – 300



84



126 + 84 = 210



300 – 400



72



210 + 72 = 282



400 – 500



66



282 + 66 = 348



500 – 600



52



348 + 52 = 400



TOTAL



f = n = 400




We have added up all the values of the frequency in the second column and have got,


Total = n = 400


Now, we just need to find the value of n/2. So,




Now, look up for a value in the cumulative frequency just greater than 200.


We have, 210.


Corresponding to this value of cumulative frequency, we can say that median class is 200 – 300.


That is,


Median class = 200 – 300


we have almost everything we require to calculate median.


Median is given by,



Where,


l = lower limit of the median class = 200


n = Total number of observation (sum of frequencies) = 400


cf = cumulative frequency of the class preceding the median class = 126


f = frequency of the median class = 84


c = class size (class sizes are equal) = 100


Putting the values, l = 200, n/2 = 200, cf = 126, f = 84 and c = 100 in the given formula of median, we get






Median = 200 + 88.09


Median = 288.09


Thus, the median of the data is 288.09.


More from this chapter

All 43 →