Question

In: Statistics and Probability

An engineer measured the Brinnel hardness of 25 pieces of ductile iron. The average hardness was...

An engineer measured the Brinnel hardness of 25 pieces of ductile iron. The average hardness was 172.52. The population standard deviation of Brinnel Hardness of ductile iron is 10.31. The engineer hypothesized the the mean Brinnel hardness of such ductile pieces is greater than 170. Test this hypothesis for a = 0.05.

Solutions

Expert Solution

Solution :

= 170

=172.52

=10.31

n = 25

This is the right tailed test .

The null and alternative hypothesis is ,

H0 :    = 170

Ha : > 170

Test statistic = z

= ( - ) / / n

= (172.52-170) / 10.31 / 20

= 0.05

Test statistic = z = 0.05

P(z > 0.05 ) = 1 - P(z < 0.05 ) = 1 - 0.5199

P-value =0.4801

= 0.05  

P-value >

0.4801 > 0.05

Fail to reject the null hypothesis .

There is not sufficient evidence to suggest that


Related Solutions

An engineer measured the Brinell hardness of 25 pieces of ductile iron from her company, that...
An engineer measured the Brinell hardness of 25 pieces of ductile iron from her company, that were subcritically annealed. She believes that the alloys her company uses in iron, will ultimately make the iron stronger, and thus will have a higher Brinell hardness score. She tests 25 pieces of ductile iron from her company with the resulting data of Brinell hardness scores: 170 167 174 179 179 187 179 183 179 156 163 156 187 156 167 156 174 170...
(15 pts) The minimal Brinell hardness for a specific grade of ductile iron is 130. An...
(15 pts) The minimal Brinell hardness for a specific grade of ductile iron is 130. An engineer has a sample of 25 pieces of this type of iron that was subcritically annealed with the Brinell hardness values as given below. The engineer would like to know whether this annealing process results in the proper Brinell hardness on average. 135 149 132 142 124 130 122 128 120 128 127 123 136 141 130 139 134 135 130 141 149 137...
What is “hardness” and how is it measured?
What is “hardness” and how is it measured?
in a study of thermal annealing process, hardness of steel is measured before annealing and after...
in a study of thermal annealing process, hardness of steel is measured before annealing and after annealing. a group of 16 samples measured and the test results are given in the table below before ann 209 178 169 212 180 192 158 180 170 153 183 165 201 179 243 144 after ann 196 171 170 207 177 190 159 180 164 152 179 162 199 173 231 140 Use the .01 level of significance to test whether the annealing...
The company Dilmart has 8,000 pieces in inventory. The average dollar value of these pieces is...
The company Dilmart has 8,000 pieces in inventory. The average dollar value of these pieces is $ 10.79 with a standard deviation equal to $ 3.34. Suppose the inventory manager selected a random sample of n = 64 pieces of inventory and found a sample mean equal to $ 11.27. The probability of obtaining a sample mean of at least $ 11.27 is approximately 0.444. Select one: True False
Describe the Rockwell hardness test. Include information on the indenter type, loading conditions and quantities measured....
Describe the Rockwell hardness test. Include information on the indenter type, loading conditions and quantities measured. Describe how an Izod impact test of a polymer specimen is performed. What does the test measure?
Reese’s pieces are supposed to be 50% orange, 25% yellow, and 25% brown. Suppose your random...
Reese’s pieces are supposed to be 50% orange, 25% yellow, and 25% brown. Suppose your random sample is of size 500. Let ?̂be the proportion of orange piece in your sample. 2. Which parameter is being estimated by ?̂? A. The true average number of orange piece in your sample. B. The true average number of orange piece in all Reese’s pieces. C. The true proportion of orange piece in your sample. D. The true proportion of orange piece in...
The absorbance of a cationic iron(II) sample solution was measured in a spectrophotometer, but the instrument...
The absorbance of a cationic iron(II) sample solution was measured in a spectrophotometer, but the instrument returned an error because the absorbance was too high. The sample was then diluted by using a pipette to take 100.0 μL of the sample and injecting it into a cuvette already containing 2.00 mL of water (total volume is 2.00 mL + 100.0 μL). The absorbance value of the diluted solution corresponded to a concentration of 7.71×10−6 M . What was the concentration...
Iron-59 has a half-life of 45.1 days. How old is an iron nail if the Fe-59 content is 25% that of a new sample of iron?
Iron-59 has a half-life of 45.1 days. How old is an iron nail if the Fe-59 content is 25% that of a new sample of iron?   Show all calculations leading to a solution.
Average yield of strain A was measured as 0.905 by 20 experiments and average yield of...
Average yield of strain A was measured as 0.905 by 20 experiments and average yield of strain B of the same organism under same experimental conditions was measured as 0.873 by 15 experiments. Standard deviation of yields of strain A was K/1000 and standard deviation of yields of strain B was (K+15)/1000 where K is the 17. a) Construct 95% confidence interval for the ratio of population variance of yields of strain A to population variance of yields of strain...
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT