Suppose the company SF Express states that their packages arrive at HKUST within three days or less on average. You want to find out whether the actual average delivery time is longer than this. You conduct a hypothesis test.

State the null and alternative hypotheses

Suppose you conclude that SF Express's average time to delivery is longer than three days; but your conclusion was wrong. What type of error did you commit? Please explain your answer.

To receive full marks for questions on Hypothesis testing :

Please state the null and alternative hypothesis, significance level, calculate the value of the z-statistic or t-statistic or Chi-square statistic.

If the question requires specifically an approach, you should follow the guideline; otherwise, feel free to use either the critical value approach or the p-value approach. If you use the critical value approach, you should write out the rejection region explicitly and draw a conclusion. If you use the p-value approach, you should calculate the p-value and draw a conclusion.

3 decimal places