Answer:
a) 48.408
b) 1.235
Step-by-step explanation:
a)
The average hardness value xbar can be computed as
xbar=sum of values/number of values
xbar=(46.5+46.9+49.4+50.3+49.8+48.8+47+47.7+48.3+49.4+47.8+49)/12
xbar=580.9/12
xbar=48.408 (rounded to 3 decimal places).
The average hardness value is 48.408.
b)
The standard deviation hardness value s can be computed as
x x-xbar (x-xbar) ²
46.5 -1.90833 3.64174
46.9 -1.50833 2.27507
49.4 0.99167 0.98340
50.3 1.89167 3.57840
49.8 1.39167 1.93674
48.8 0.39167 0.15340
47.0 -1.40833 1.98340
47.7 -0.70833 0.50174
48.3 -0.10833 0.01174
49.4 0.99167 0.98340
47.8 -0.60833 0.37007
49.0 0.59167 0.35007
Total 16.7692
s=1.235 (rounded to 3 decimal places)
The standard deviation hardness value is 1.235.