Testing Gas Mileage Claims

Testing Gas Mileage Claimsassume That You Are Working For The Consumer

Testing Gas Mileage Claimsassume That You Are Working For The Consumer

Testing Gas Mileage Claims Assume that you are working for the Consumer Protection Agency and have recently been getting complaints about the highway gas mileage of the new Dodge Caravans. Chrysler Corporation agrees to allow you to randomly select 40 of its new Dodge Caravans to test the highway mileage. Chrysler claims that the Caravans get 28 mpg on the highway. Your results show a mean of 26.7 and a standard deviation of 4.2. You support Chrysler’s claim.

1. Show why you support Chrysler’s claim by listing the P-value from your output. After more complaints, you decide to test the variability of the miles per gallon on the highway. From further questioning of Chrysler’s quality control engineers, you find they are claiming a standard deviation of 2.1. 2.

Test the claim about the standard deviation. 3. Write a short summary of your results and any necessary action that Chrysler must take to remedy customer complaints. 4. State your position about the necessity to perform tests of variability along with tests of the means.

Section 8–5Testing Gas Mileage Claims 1. The hypotheses are H0: μ = 28 and H1: μ ≠ 28. The value of our test statistic is t ≈ 1.96, and the associated P-value is 0.0287. We would reject Chrysler’s claim that the Dodge Caravans are getting 28 mpg. 2. The hypotheses are H0: σ² = 2.1² and H1: σ² ≠ 2.1². The value of our test statistic is approximately zero, and the associated P-value is very close to zero. We would reject Chrysler’s claim that the standard deviation is 2.1 mpg.

We support Chrysler’s claim about the mean mileage but reject their claim regarding the variability in miles per gallon. This suggests inconsistent quality control, leading to customer dissatisfaction. To address this, Chrysler must improve their manufacturing process to reduce the variability in highway gas mileage, ensuring more consistent performance and better customer experiences.

Furthermore, this case exemplifies the importance of conducting both tests of means and variability. Testing just the mean may overlook inconsistencies in product quality, which variability tests can highlight. When considering consumer protection policies, regulatory agencies should advocate for comprehensive testing that encompasses both the central tendency and dispersion to ensure product claims are robustly validated. This comprehensive testing approach can prevent overpromising and underdelivering, ultimately promoting fair business practices and consumer trust.

In conclusion, the statistical evidence supports a rejection of Chrysler’s claim about average highway mileage, as indicated by the P-value of 0.0287. Additionally, the test results on variability strongly suggest that the claim regarding the standard deviation is invalid. Chrysler must undertake corrective measures to tighten the mileage distribution and align their manufacturing processes with quality standards. Only through rigorous testing of both the mean and variability can consumer protection agencies effectively safeguard consumer interests and promote transparency in product claims.

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