Q9 of 69 Page 7

The following table gives the distribution of the life time of 400 neon lamps:


We have n = 400


So,


The cumulative Frequency just greater than is 216 then the median class is 3000-3500 such that


the lower limit (l) = 3000


cumulative frequency of the class preceding 3000-3500 (cf) = 130


frequency of the median class 3000-3500 = 86,


class size (h) = 500


Using the formula,, we have




= 3000 + 406.98


= 3406.98


So, median life time of lamps is 3406.98hours


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