Question

an engineer measured brinell hardness of 25 pieces of ductile iron that were sub critically annealed the resulting data were 170 167 174 179 179 187 179 183 179 156 163 156 187 156 167 156 174 170 183 179 174 179 170 159 187 test hypothesis of all such ductile iron piece is 170

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Answer 1

Given:

Total number of pieces(n) = 25

The resulting data : 170 167 174 179 179 187 179 183 179 156 163 156 187 156 167 156 174 170 183 179 174 179 170 159 187

To test:

Test the hypothesis that the mean of all such ductile iron piece is 170

Calculation:

The sample mean of the above data is given by the formula

    $\bar{x}=\Sigma{\frac{x_{i}}{n} }$

       $=\frac{4675}{25}$