Question

Companies often develop and test hypotheses about their products. For example, car manufacturers will test their cars to determine fuel efficiency and miles per gallon. To ensure that products are safe and that they perform as advertised, regulatory and consumer protection groups also test companies’ claims. For this Assignment, you are working at a firm that conducts independent testing for heavy industry. Recently, an automobile manufacturer has been in the news for complaints about the highway gas mileage of their latest model minivan. You receive a contract from a consumer action group to test and write a report on the company’s claim that its minivans get 28 miles per gallon on the highway. The car company agrees to allow you to select randomly 35 low-mileage fleet minivans to test their highway mileage. Your test results gave you the following data: 29.7 24.5 27.1 29.8 29.2 27.0 27.8 24.1 29.3 25.9 26.2 24.5 32.8 26.8 27.8 24.0 23.6 29.2 26.5 27.7 27.1 23.7 24.1 27.2 25.9 26.7 27.8 27.3 27.6 22.8 25.3 26.6 26.4 27.1 26.1 Include a brief introduction that provides a context for the assignment you have been given by your firm. Calculate a 95% confidence interval around your sample mean. (75 words, or 1 paragraph) Note: Include your calculations. If your calculations are submitted separately, make note of where they can be found. Is the company’s claimed mean inside your confidence interval? (75 words, or 1 paragraph) What does that result indicate about the company’s claim? (75 words, or 1 paragraph)

Answer 1

Since upper bound of confidence interval < 28, so at 95% confidence level or 5% significance level, we can conclude that there is not sufficient evidence to support the company's claim.