There is an old belief that red cars get pulled over for speeding more frequently than cars of other colors. To test whether in fact there is any difference in speeding (as opposed to just biased enforcement), a random sample of red cars and non-red cars are clocked by radar in a 55 mph zone.
|
Red cars
|
Non-red cars
|
|
N
|
25
|
60
|
|
Mean
|
62.8
|
59.6
|
|
Standard deviation
|
5.1
|
4.2
|
- What is the research hypothesis?
- What are the degrees of freedom?
- Based upon the given alpha and the degrees of freedom in Part (b), what is the critical value?
- Calculate the t-statistic (test statistic).
- Do you reject or fail to reject the null hypothesis? What does this mean in terms of biased enforcement?