Question D

A Police Officer believed that the average speed of cars travelling over a certain stretch of highway exceeds the posted limit of 60km/h. The speeds of a random sample of 20 cars were recorded. The average speed was found to be 61km/h with a standard deviation of 5km/h. Is there sufficient evidence, at the 5% significance level, to support the officer's belief?

1. State the null hypothesis in words AND statistical notation.

2. State the alternate hypothesis in words AND statistical notation.

3. Calculate the appropriate test statistic.

4. What is your decision in terms of this example?

5. What is your conclusion in relation to the original question?