Answer:
If the slopes of the lines are both zero, the lines are horizontal and are parallel by definition. Since the slopes of vertical lines are undefined and not considered equal, vertical lines will not be considered.
I hope this helps you :)
Answer:
This means that we are 80% confident that the mean of the drive-through service time is between 178.0 seconds and 181.0 seconds. This conclusion was obtained after examined 576 customers. If you want a greater % of confidence you will have to lower the lower bound and increase the upper bound
