Question

It has been reported that the standard deviation of the speeds of drivers on Interstate 75 near Findlay, Ohio, is 8 miles per hour for all vehicles. A driver feels from experience that this is very low. A survey is conducted, and for 50 drivers the standard deviation is 10.5 miles per hour. Use a 0.05 significance level to test the claim that the standard deviation of all speeds of drivers on Interstate 75 near Findley, Ohio is greater than 8 miles per hour for all vehicles.

1. State the hypotheses and identify the claim

2. Find the critical value or values

3. Find the test statistic. First state the calculator command used to find it.  

4. Make the decision about the null hypothesis

5. Draw conclusion about the claim

Answer 1

(1)

(2) D.F = n-1 = 49

(3)

(4) By decision rule, we reject H0.

(5) That is , there is sufficient evidence to conclude that standard deviation of all speeds of drivers on Interstate 75 near Findley, Ohio is greater than 8 miles per hour for all vehicles.