The following table gives the distribution of the life time of 400 neon lamps:
Life time (in hours) | Number of lamps |
1500 - 2000 2000 - 2500 2500 - 3000 3000 - 3500 3500 – 4000 4000 - 4500 4500 – 5000 | 14 56 60 86 74 62 48 |
Find the median life time of a lamp
The cumulative frequency of the given data can be calculated as:
Life time (in hours) | Number of lamps | Cumulative Frequency |
1500 - 2000 2000 - 2500 2500 - 3000 3000 - 3500 3500 – 4000 4000 - 4500 4500 – 5000 | 14 56 60 86 74 62 48 | 14 70 130 216 290 352 400 |
As per the question,
N= 400
Hence,
Median class = 3000-3500
Lower limit, l = 3000
cf = 130
f = 86
h = 500
Now,
Median can be calculated as:
= 3000 + 406.97
= 3406.97
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