An engineer measured the Brinell hardness of 25 pieces ofductile iron from her company, that were subcritically annealed.She believes that the alloys her company uses in iron, willultimately make the iron stronger, and thus will have a higherBrinell hardness score. She tests 25 pieces of ductile iron fromher company with the resulting data of Brinell hardnessscores:
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
The engineer hypothesizes that the mean Brinell hardness score ofsuch ductile iron pieces from her company will greater than knownaverage Brinell score for iron which is 170.
At the 5% level of significance, is there enough evidence toconclude this?
1) Step 1: State the Claims which means to State the null andalternative hypotheses. Use correct math type. You may want toconsider looking back at the symbols assignment from the beginningof class.
2).
a) What is the sample mean? Use 4 decimal places.
b) What is the sample standard deviation? Use 4 decimalplaces.
c) Are the normality assumptions met?
3) Step 3: Assessment of Evidence. Find the pvalue and upload animage of the normal curve with the test statistic indicated and thecorrect area of the curve shaded. This shaded area is thepvalue.
a) What is the pvalue? Use 4 decimal places.
b) Upload an image of the normal curve with the test statisticindicated and the correct area of the curve shaded. This shadedarea is the pvalue.
4) Step 4: Conclusion. State your conclusion. Either reject orfail to reject H0H0 , indicate why, then write the conclusion interms of the problem.
