Answer:
We know that In 1990, the mean duration of long-distance telephone calls originating in one town was 7.2 minutes. And we want to test if the mean duration of long-distance phone calls has changed from the 1990 mean of 7.2 minutes (alternative hypothesis) and the complement rule would represent the null hypothesis.
The correct system of hypothesis are:
Null hypothesis:
Alternative hypothesis:
So then the best option for this case would be:
H0: μ = 7.2 minutes Ha: μ ≠ 7.2 minutes
Step-by-step explanation:
We know that In 1990, the mean duration of long-distance telephone calls originating in one town was 7.2 minutes. And we want to test if the mean duration of long-distance phone calls has changed from the 1990 mean of 7.2 minutes (alternative hypothesis) and the complement rule would represent the null hypothesis.
The correct system of hypothesis are:
Null hypothesis:
Alternative hypothesis:
So then the best option for this case would be:
H0: μ = 7.2 minutes Ha: μ ≠ 7.2 minutes
And in order to test the hypothesis we can use a one sample t test or z test depending if we know the population deviation or not