Q. 74.2( 6 Votes )
To find mean, we will solve by direct method:
We have got
Σfi = 30 & Σfixi = 6150
∵ mean is given by
To find median,
Assume Σfi = N = Sum of frequencies,
h = length of median class,
l = lower boundary of the median class,
f = frequency of median class
and Cf = cumulative frequency
Lets form a table.
So, N = 30
⇒ N/2 = 30/2 = 15
The cumulative frequency just greater than (N/2 = ) 15 is 25, so the corresponding median class is 200 - 250 and accordingly we get Cf = 13(cumulative frequency before the median class).
Now, since median class is 200 - 250.
∴ l = 200, h = 50, f = 12, N/2 = 15 and Cf = 13
Median is given by,
= 200 + 8.33
Hence, mean is 205 and median is 208.33
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