Item (x)



5



7



9



12



14



17



19



21



Frequency (f)



6



5



3



6



5



3



2



4


Draw the table as below,


Items (x)



Frequency (f)



Cumulative frequency



Fx



5



6



6



30



7



5



11



35



9



3



14



27



12



6



20



72



14



5



25



70



17



3



28



51



19



2



30



38



21



4



34



84




N = 34




∑fx = 407



We have;


N = 34 (even number)


Median =





Now,


∑fx = 407 and ∑f = N = 34


Mean =


Hence,


Mode = 3(median) – 2 (mean)


= 3×12 - 2×11.97


= 36 – 23.94


= 12.06


7