In a study on speed control, it was found that the main reasons for regulations were to make traffic flow efficient and to minimize the risk of danger. An area that was focused on in the study was the distance required to completely stop a vehicle at various speeds. Use the following table to answer the questions.

MPH	Braking distance (yrds)
5	10
10	17
20	27
30	50
40	60
50	100
60	150
70	200

Assume MPH is going to be used to predict stopping distance.

Questions

1. Which of the two variables is the dependent variable (Y) Why?
2. Which is the independent variable? Why?
3. What type of variable (quantitative: continuous or discrete; qualitative: nominal or rank) is the independent variable?
4. What type of variable is the dependent variable? Seeabove
5. Construct a scatter plot for the data. Labelyour X and Y axes and show the points.
6. Is there a relationship between the two variables? And if so, is it positive or negative? Why?
7. Suppose the correlation coefficient (r) is 0.956? Does this suggest a strong relationship? Explain
8. What would you conclude about the relationship if r=0?
9. Does correlation mean causation? Explain.