An particular car is claimed to get an average of 28 mpg A r

An particular car is claimed to get an average of 28 mpg. A random sample of 12 cars are tested and the following fuel consumption is observed (mpg): Does this data suggest this car averages more than 28 mpg at the 0.05 level of significance?

Solution

We wish to test the null hypothesis:

H₀: The car average is 28 mpg.

against

H₁: The car average is greater than 28 mpg. (right tailed)

We will perform single sample mean test using R - software

t.test(a, mu = 28, alternative = \"greater\")

One Sample t-test

data: a
t = 2.2921, df = 11, p-value = 0.02131
alternative hypothesis: true mean is greater than 28
95 percent confidence interval:
28.17681 Inf
sample estimates:
mean of x
28.81667

p-value = 0.02131 < 0.05 hence we will reject the null hypothesis and conclude that car average is greater than 28 mpg