The data file Trucks contains data on a sample of 200 trucks that were weighed on two scales. The WIM (weigh-in-motion) scale weighs the trucks as they drive down the highway. The POE scale weighs the trucks while they are stopped at the port-of-entry station. The maker of the WIM scale believes that its scale will weigh heavier than the POE scale 60% of the time when gross weight is considered.
a. Create a new variable that has a value = 1 when the WIM gross weight 7 POE gross weight, and 0 otherwise.
b. Determine the sample proportion of times the WIM gross weight exceeds POE gross weight.
c. Based on this sample, what is the probability of finding a proportion less than that found in part b? For this calculation, assume the WIM maker’s assertion is correct.
d. Based on the probability found in part c, what should the WIM maker conclude? Is his 60% figure reasonable?