The property manager of a shopping mall claims that the mean score of their customer service is at least 85.Twenty-five customers were randomly selected to evaluate the customer service of the mall. The analysis via a hypothesis test shows that the P-value is less than 0.002 (i.e. p < 0.002).

a. State the null and alternative hypotheses.

b. Which distribution, normal or Student's t-distribution, is more appropriate for the hypothesis test? Why?

c. Explain the results of the hypothesis test in a way that could be understood by someone who has not studied statistics.