Question

In the year 2000, the average car had a fuel economy of 22.6 MPG. You are curious as to whether the average in the present day is less than the historical value. What are the appropriate hypotheses for this test

Answer 1

The appropriate null hypothesis is
`H_0: \mu = 22.6`

The appropriate alternative hypothesis is
`H_1: \mu < 22.6`

Explanation:

The average car had a fuel economy of 22.6 MPG. Test if the current average is less than this.

At the null hypothesis, we test if the current average is still of 22.6 MPG, that is:

`H_0: \mu = 22.6`

At the alternative hypothesis, we test if the current mean has decreased, that is, if it is less than 22.6 MPG. So

`H_1: \mu < 22.6`