5.8 Fuel efficiency of Prius: Fueleconomy.gov, the official US government source for fuel economy information, allows users to share gas mileage information on their vehicles. The histogram below shows the distribution of gas mileage in miles per gallon (MPG) from 14 users who drive a 2012 Toyota Prius. The sample
(a) The EPA claims that a 2012 Prius gets 50 MPG (city and highway mileage combined). Do these data provide strong evidence against this estimate for drivers who participate on fueleconomy.gov?
The hypotheses for the test are:
- Ho: μ = 50
Ha: μ < 50 - Ho: μ = 50
Ha: μ ≠ 50 - Ho: μ = 50
Ha: μ > 50
To execute this hypothesis test we should use a:
- Z-test
- T-Test
because:
- σ is known, but the
sample size is less than 30 - σ is known and the population is normal
- σ is unknown and the sample size is less than 30
There are ______ degrees of freedom for this test.
The test statistic is: _______________ (please round to two decimal places)
The p-value for this hypothesis test is: __________ (please round to four decimal places)
The conclusion for the hypothesis test is:
- Since p<α we reject the null hypothesis and accept the alternative
- Since p ≥ α we accept the null hypothesis
- Since p ≥ α we reject the null hypothesis and accept the alternative
- Since p ≥ α we do not have enough evidence to reject the null hypothesis
- Since p<α we fail to reject the null hypothesis
(c) Calculate a 95% confidence interval for the average gas mileage of a 2012 Prius by drivers who participate on fueleconomy.gov.
We are __________ % confident that the true population gas mileage of a 2012 Prius by drivers who participate on fueleconomy.gov is between ______ mpg and _______ mpg. (please round to one decimal place)
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