Variance and average

Of the 40 values were calculated average mx = 7.5 and variance sx = 2.25. After we found the control to lack the two items of the values of x41 = 3.8 and x42=7. Correct the above characteristics (mx and sx).

Correct answer:

m2 =  7.4
r2 =  2.4552

Step-by-step explanation:

m1=7.5 r1=2.25 n1=40  x41=3.8 x42=7 n2=n1+2=40+2=42  m2=n2n1 m1+x41+x42=4240 7.5+3.8+7=7.4
r1 = n1   (xm1)2 / n1  x=r1+m1=2.25+7.5=9  r2=n2n1 (xm1)2+(x41m2)2+(x42m2)2=4240 (97.5)2+(3.87.4)2+(77.4)2=2.4552



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Showing 1 comment:
Mathematican
When determining the resulting mean, proceed as follows. The 40 xi elements are loaded with their mean and the two missing values added. That is the sum of 42 values is calculated, where the first 40 values are 7.5 and the 41st is 3.8 and the 42nd is 7. The sum is divided by the number of elements 42 and the corrected resulting average is obtained.

When calculating the variance, the procedure is similar. The variance is the average of the squared deviations from the average. 40 values will be replaced by calculated x. Let's determine x from the average and flood dispersion x=9. We replace the 40 elements with this number and add the two missing ones to calculate the corrected variance.





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