In a comparison of the strengths of concrete produced by four experimental mixes, three specimens were prepared from each type of mix. Each of the 12 specimens was subjected to increasingly compressive loads until breakdown. The accompanying table gives the compressive loads, in tons per square inch, attained at breakdown. Specimen numbers 1-12 are indicated in parentheses for identification purposes.
| Mix A |
Mix B |
Mix C |
Mix D |
| (1)2.30 |
(2)2.20 |
(3)2.15 |
(4)2.25 |
| (5)2.20 |
(6)2.10 |
(7)2.15 |
(8)2.15 |
| (9)2.25 |
(10)2.20 |
(11)2.20 |
(12)2.25 |
a. Assuming that the requirements for a one-way layout are met, analyze the data. State whether there is statistical support at the α = .05 level of significance for the conclusion that at least one of the concretes differs in average strength from the others.
b. Applet Exercise Use the applet F-Ratio Probabilities and Quantiles to find the p-value associated with the test in part (a).