Question

Compute the range and sample standard deviation for strength of the concrete (in psi). 3980, 4100, 3500, 3200, 2950, 3850, 4100, 4020 The range is 1150 psi. S= psi (Round to one decimal place as needed.)

Answer 1

Solution :

a) The range is given as follows :

Range = Maximum value - Minimum value

Range = 4100 - 2950

Range = 1150

The range is 1150 psi.

b) The sample standard deviation is given as follows :

n 1 2 S= E(T - ) n-14 i=1

Where, xi's are sample values, n is sample size and

1 IS = Σ X; is sample mean. n 1=1

We have, n = 8

1 - (3980 +4100 + .……. + 4020)

29700 =3712.5 8

..SE 1 - [(3980 – 3712.5)2 +. 8 - 1 ............. + (4020 – 3712.5)2]

..S= 1374550 7

..s= 443.1

The sample standard deviation is s = 443.1 psi.

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