Find the mean, median and mode of the following data:
Classes: | 0-20 | 20-40 | 40-60 | 60-80 | 80-100 | 100-120 | 120-140 |
Frequency: | 6 | 8 | 10 | 12 | 6 | 5 | 3 |
Class interval | Mid value(x) | Frequency(f) | fx | Cummulative frequency |
0-20 | 10 | 6 | 60 | 6 |
20-40 | 30 | 8 | 240 | 14 |
40-60 | 50 | 10 | 500 | 24 |
60-80 | 70 | 12 | 840 | 36 |
80-100 | 90 | 6 | 540 | 42 |
100-120 | 110 | 5 | 550 | 47 |
120-140 | 130 | 3 | 390 | 50 |
Total | N=50 |
Mean= =
We have, N= 50,
N/2 = 25
Hence, median class =60-80, such that
l=60, f’=12, f=24, h=20
Median = l +
Here, we may observe that maximum class frequency is 12 belonging to the class interval 60-80
So, modal class= 60-80
Lower limit, l= 60
f0=10, f2=6, f=12,h = 20
=