The State Transportation Department Is Thinking of Changing Its Speed

Multiple Choice

The State Transportation Department is thinking of changing its speed limit signs. It is considering two new options in addition to the existing sign design. At question is whether the three sign designs will produce the same mean speed. To test this, the department has conducted a limited test in which a stretch of roadway was selected. With the original signs up, a random sample of 30 cars was selected and the speeds were measured. Then, on different days, the two new designs were installed, 30 cars each day were sampled, and their speeds were recorded. Suppose that the following summary statistics were computed based on the data: Based on these sample results and a significance level equal to 0.05, assuming that the null hypothesis of equal means has been rejected, the Tukey-Kramer critical range is:

A) 1.96.
B) approximately 4.0.
C) Can't be determined without more information
D) None of the above