Q.1. Calculate mean , standard deviation and variance :
Variable : 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40
frequency : 2 5 7 13 21 16 8 3
Q.2. The number examined , the meanweight and standard deviation in each group of examination by two medical examiners are given below . calculate mean and standard deviation of both the group taken together .
Medical examiner number examined mean weight (lbs) standard deviation (lbs)
A 50 113 6.5
B 60 120 8.2
Q.3. You are given the following data about height of boys and girls :
Boys Girls
Number 72 38
Average height (in inches) 68 61
Variance of distribution (in inches) 9 4
(a) calculate cofficient of variation
(b) decide whose height is more variable .
Solution 1
X | f | m | fm |
|
|
---|---|---|---|---|---|
0-5 | 2 | 2.5 | 5 | 6.25 | 12.5 |
5-10 | 5 | 7.5 | 37.5 | 56.25 | 281.25 |
10-15 | 7 | 12.5 | 87.5 | 156.25 | 1093.75 |
15-20 | 13 | 17.5 | 227.5 | 306.25 | 3981.25 |
20-25 | 21 | 22.5 | 472.5 | 506.25 | 10631.25 |
25-30 | 16 | 27.5 | 440 | 756.25 | 12100 |
30-35 | 8 | 32.5 | 260 | 1056.25 | 8450 |
35-40 | 3 | 37.5 | 112.5 | 1406.25 | 4218.75 |
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Solution 3
| Boys | Girls |
Number | 72 | 38 |
Average Height | 68 | 61 |
Variance of Distribution
| 9 | 4 |
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