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?