Answer:
[tex]H_{0}:[/tex] μ=3.13 (the mean number of residents in the Arizona retirement communities is 3.13)
Step-by-step explanation:
Alternative hypothesis would be:
[tex]H_{a}:[/tex] μ<3.13
Then z-score of the sample of 25 households in Arizona retirement communities with mean number 2.86 residents per household and the standard deviation of 1.20 residents is calculated under the assumptions of null hypothesis and checked against the critical value of a given significance level.