Question

In 1990, the average duration of long-distance telephone calls originating in one town was A long-distance telephone company wants to perform a hypothesis test to determine whether the average duration of long-distance phone calls has changed from the 1990 mean of The hypotheses are:

Answer 1

The null hypothesis is
`H_0: \mu = X`

The alternate hypothesis is
`H_1: \mu \\eq X`

Explanation:

Mean of X in 1990, test if the mean duration has changed:

At the null hypothesis, we test if the mean duration is still X, that is:

`H_0: \mu = X`

At the alternate hypothesis, we test if the mean duration has the changed, that is, if it is different of X. So

`H_1: \mu \\eq X`