It’s seen that, the cumulative frequency just greater than \(\frac{n}{2}\) (\(\frac{400}{2}\) = 200) is 216 and it belongs to the class interval 3000 – 3500 which becomes the Median class = 3000 – 3500
Lower limits (l) of median class = 3000 and,
Frequency (f) of median class = 86
Cumulative frequency (cf) of class preceding median class = 130
And, the Class size (h) = 500
Thus, calculating the median by the formula, we get
= 3000 + (\(\frac{35000}{86}\))
= 3406.98
Thus, the median life time of lamps is 3406.98 hours.
