15.56 A developer is hiring a construction company for their new project. The developer’s main concern is the project’s completion time. To determine the completion time for a construction project of its size, the developer retrieved six previous projects’ completion times from four construction companies. From the data collected, the developer determines that the sum of squares delivery time is 1439.278, and the sum of squares delivery time within each construction company is 2958.042.

a. Use the provided information to prepare the analysis of variance table.

b. Test the null hypothesis that the population mean completion times are the same for the construction companies.