A market research study is undertaken to test which of two popular electric shavers, a model made by Norelco or a model made by Remington, is preferred by consumers. A random sample of 25 men who regularly use an electric shaver, but not one of the two models to be tested, is chosen. Each man is then asked to shave one morning with the Norelco and the next morning with the Remington, or vice versa. The order, which model is used on which day, is randomly chosen for each man. After every shave, each man is asked to complete a questionnaire rating his satisfaction with the shaver. From the questionnaire, a total satisfaction score on a scale of 0 to 100 is computed. Then, for each man, the difference between the satisfaction score for Norelco and that for Remington is computed. The score differences (Norelco score – Remington score) are 15, –8, 32, 57, 20, 10, –18, –12, 60, 72, 38, –5, 16, 22, 34, 41, 12, –38, 16, –40, 75, 11, 2, 55, 10. Which model, if either, is statistically preferred over the other? How confident are you of your finding? Explain.