This riddle has been around for some time on internet platforms such as Instagram, Facebook, and WhatsApp, and many people still argue over what the answer might be, as there are many possibilities. The correct answer is There is no way to get an average speed of 30 mph (miles per hour). If your average speed for the 2 miles stretch must be 30 mph, you should do it in 4 minutes. During the ascent, you would have already taken 4 minutes to travel 1 mile at 15 mph. Since you have taken 4 minutes to go up the hill, you will need to take 0 seconds to travel the 1 mile descent in order to get an average speed of 30 mph. This is not possible.