# Hypothesis Testing & Confidence Interval

4.48. An experiment was carried out on scale models in a wave tank to investigate how the choice of mooring method affected the bending stress produced in a device used to generate electricity from wave power at sea. The model system was subjected to the same sample of 18 sea states with each of the two mooring methods. The resulting data (root mean square bending moment in Newton meters) are

Sea state Method 1 Method 2

1 2.23 1.82

2 2.55 2.42

3 7.99 8.26

4 4.09 3.46

5 9.62 9.77

6 1.59 1.4

7 8.98 8.88

8 0.82 0.87

9 10.83 11.2

10 1.54 1.33

11 10.75 10.32

12 5.79 5.87

13 5.91 6.44

14 5.79 5.87

15 5.5 5.3

16 9.96 9.82

17 1.92 1.69

18 7.38 7.41

a. Conduct the appropriate hypothesis test using a 0.10 significance level.

b. Construct a 90% confidence interval for the true mean difference in bending stress.

c. What did you assume to do the analysis? Can you evaluate how well these data meet the assumptions? If yes, determine how comfortable you are with them. If not, explain why.

See attached file.

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#### Solution Summary

The solution provides step by step method for the calculation of testing of hypothesis and confidence interval for mean difference. Formula for the calculation and Interpretations of the results are also included. Interactive excel sheet is included. The user can edit the inputs and obtain the complete results for a new set of data.