If the sum of squares of 10 positive numbers is 370 and the variance is 33, then the average is () A. 1B. 2C. 3D. 4

If the sum of squares of 10 positive numbers is 370 and the variance is 33, then the average is () A. 1B. 2C. 3D. 4

According to the meaning of the question: 33 = 110 (370-10. X2), and 10 numbers are positive, so the average. X = 370 △ 10 − 33 = 2

If the variance of a set of data is 33 and their sum of squares is 370, then their average may be ()
A 1,B 2,C 3,D 4.

Variance formula: S = 1 / N (sum of squares - n × mean ^ 2)
Let this set of data have n numbers
33n = 370-n * mean & sup2;
If the mean is 1, n has no integer solution,
If the average is 2, then n = 10
If the mean is 3, n has no integer solution
If the average is 4, n has no integer solution
Choose B

If the sum of squares of 10 data is 1723 and the average is 13, then its variance is____ ?

x1^2+x2^2+… +x10^2=1723(x1+x2+… X10) / 10 = 13, so X1 + x2 + X10 = 130 variance = (x1-13) ^ 2 + (x2-13) ^ 2 + +(x10-13)^2=(x1^2+x2^2+… +x10^2)-2×13(x1+x2+… x10)+10×13^2=1723-26×130+1690=33