3) 5r-7 = 2r+14
3r=21
r= 7
4) 5(n-7)=2(n+41)
5n -35=2n+82
3n=117
n=39
5) 3(x-2)=9x
3x-6=9x
-6=6x
-1=x
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Variance is the average of the square of the differences of each data with the mean. To calculate for the variance, we first calculate for the mean. Then, we subtract each data with the mean. Next, each difference would be squared and added. The resulting value would be divided on how many data are used. We calculate as follows:
Mean = <span>9 + 7 + 6.5 </span>+ 7.5 + 7 + 8 + 5 + 6 + 7.5 + 8 / 10
Mean = 6.4
Squared of the sum of the differences = (9-6.4)^2 + (7-6.4)^2 + (6.5-6.4)^2 + (7.5-6.4)^2 + (7-6.4)^2 + (8-6.4)^2 + (5-6.4)^2 + (6-6.4)^2 + (7.5-6.4)^2 + (8-6.4)^2 = 17.15
Variance = 17.15 / 10 = 1.715
