Blake has entered a mountain bike competition at Starvation Flats Bike Park. Placement in the competition is determined by a person's average speed over four laps around the course. The course itself is of a mile long. If Blake completed the four laps in 12 minutes, then his average speed around the track is
miles per hour.
First, we need to convert the time from minutes to hours by dividing by 60: 12 minutes / 60 minutes/hour = <<12/60=0.2>>0.2 hours
Next, we divide the total distance traveled (4 laps * 1 mile per lap = <<4*1=4>>4 miles) by the time it took to travel that distance to find the average speed: 4 miles / 0.2 hours = <<4/0.2=20>>20 miles per hour. Answer: \boxed{20}.