Paragon International University
PART II: Exercises
[Totally 40 points.]
1. \( [20 \) points \( ] \) A company claims that the average delivery time for its packages is 2.5 days. A sample of 20 deliveries has a mean time of 2.8 days with a standard deviation of 0.5 days.
a. At the \( 5 \% \) significance level, is there enough evidence to conclude that the average delivery time is different from 2.5 days?
i. State the null and alternative hypotheses
ii. Conduct the t-test and interpret the result