Following is the distribution of I.Q of 100 students. Find the median I.Q.
I.Q: | 55-64 | 65-74 | 75-84 | 85-94 | 95-104 | 105-114 | 115-124 | 125-134 | 135-144 |
No. of students: | 1 | 2 | 9 | 22 | 33 | 22 | 8 | 2 | 1 |
Class interval (exclusive) | Class interval (inclusive) | Frequency | Cumulative frequency |
55-64 | 54.5-64.5 | 1 | 1 |
65-74 | 64.5-74.5 | 2 | 3 |
75-84 | 74.5-84.5 | 9 | 12 |
85-94 | 84.5-94.5 | 22 | 34 (F) |
95-104 | 94.5-104.5 | 33 (f) | 37 |
105-114 | 104.5-114.5 | 22 | 89 |
115-124 | 114.5-124.5 | 8 | 97 |
125-134 | 124.5-134.5 | 2 | 99 |
135-144 | 134.5-144.5 | 1 | 100 |
N = 100 |
We have, N = 100
= 
= 50
The cumulative frequency just greater than 
is 67 then the median class 94.5-104.5 such that,
l = 94.5, f = 33, F = 34, h = 104.5 – 94.5 = 10
Median = l + 
* h
= 94.5 + 
* 10
= 94.5 + 
* 10
= 94.5 + 4.85 = 99.35
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