5. The following table gives the distribution of the life time of 400 neon lamps :
Find the median life time of a lamp.
Class |
Frequency
|
Cumulative Frequency |
1500-2000 | 14 | 14 |
2000-2500 | 56 | 70 |
2500-3000 | 60 | 130 |
3000-3500 | 86 | 216 |
3500-4000 | 74 | 290 |
4000-4500 | 62 | 352 |
4500-5000 | 48 | 400 |
Therefore, Median class = 3000-3500
Lower limit, l = 3000; Class height, h = 500
Frequency corresponding to median class, f = 86
Cumulative frequency of the class preceding the median class, c.f. = 130
Thus, the median lifetime of a lamp is 3406.97 hours
Thus, the median length of the leaves is 146.75 mm