Reference no: EM13261710

An aircraft manufacturing company  is designing a new passenger seat.  Currently  three models have been produced. The company  wishes to know which is the best model to  adopt for the aircraft based on the following variables:

                        safety

                        comfort

                        durability

                        life-cycle cost

The company  wishes to use  "hard" data from  tests and "soft" data from surveys.

Suppose the mean life-cycle cost for the present seats in a  C4P  aircraft  is  $456.34  with a standard deviation of  $34.56.  Suppose also that we estimate the mean life-cycle costs for a sample of  20 model A seats  to be  $442.50 with a standard deviation of  $32.78.  We wish to know if we can claim that model A seats have a lower  life-cycle cost than present  seats.  

            A.  State  appropriate null and alternative hypotheses in words and symbols.

            B.Test the hypothesis at the 0.05  level. What is the value of the test statistic calculated from the sample data?                    What is the critical value of the test statistic?

            C. Make a decision to reject or fail to reject the null  based on the answers in part B. Draw and label a sketch showing the test statistic and critical value.  Give the reason for rejecting or failing to reject the null.

            D. Draw a conclusion about  claim stated in the problem. Is it supported or not supported by the test results?