Q.1. Calculate mean , standard deviation and variance :
Variable : 05 510 1015 1520 2025 2530 3035 3540
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 



05  2  2.5  5  6.25  12.5 
510  5  7.5  37.5  56.25  281.25 
1015  7  12.5  87.5  156.25  1093.75 
1520  13  17.5  227.5  306.25  3981.25 
2025  21  22.5  472.5  506.25  10631.25 
2530  16  27.5  440  756.25  12100 
3035  8  32.5  260  1056.25  8450 
3540  3  37.5  112.5  1406.25  4218.75 






Solution 3
 Boys  Girls 
Number  72  38 
Average Height  68  61 
Variance of Distribution
 9  4 
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