Answer
b) 7.8
Work Step by Step
$151.6+159.2+163.5+164.1+165.1+171.4+173.2+174.3+174.8+177.6$
Sum of observations: 1674.8
# observations: 10
Mean observation: 1674.8/10 = 167.48
$(151.6-167.48)+(159.2-167.48)+163.5-167.48)+(164.1-167.48)+(165.1-167.48)+(171.4-167.48)+(173.2-167.48)+(174.3-167.48)+(174.8-167.48)+(177.6-167.48)$
$-15.88+(-8.28)+(-3.98)+(-3.38)+(-2.38)+3.92+5.72+6.82+7.32+10.12$
0 (sum of differences)
$((-15.88)^2+(-8.28)^2+(-3.98)^2+(-3.38)^2+(-2.38)^2+3.92^2+5.72^2+6.82^2+7.32^2+10.12^2)/10$
$\frac{(252.1744+68.5584+15.8404+11.4244+5.6644+15.3664+32.7184+46.5124+53.5824+102.4144)}{10 - 1}
=\frac{604.256}{10 - 1}$
$=60.4256$ (variance)
$ deviation=\sqrt{ 60.4256} $
$=7.8$
