A production supervisor at a major chemical company must determine which of two catalysts, catalyst XA or catalyst ZB, maximizes the hourly yield of a chemical process. In order to compare the mean hourly yields obtained by using the two catalysts, the supervisor runs the process using each catalyst for ten one-hour periods. The resulting yields (in kg per hour) for each catalyst are given in the table below.

Assuming that all other factors affecting yields of the process have been held as constant as possible during the test runs, it seems reasonable to regard the ten observed yields for each catalyst as a random sample of all possible yields for the given catalyst.

Complete the following tasks manually, i.e., with your hand calculator and the relevant statistical table.

(a) Use the sample data to find out whether the yield populations of the two catalysts have different variances. Use = 0.05.

State the null and alternative hypotheses and the decision rule, calculate the test statistic, make a statistical decision and draw your conclusion. Show the details of your manual calculations. What assumptions are required by the test you have just performed? Are these assumptions likely satisfied?

ZB 350 363 369 318 356 361 379 329 372 355 387 361 363 331 373 330 369 376 376 329 ZB 350 363 369 318 356 361 379 329 372 355 387 361 363 331 373 330 369 376 376 329