The object of this quiz is to adjust each circle’s radius so it contains the target population shown at the right but ONLY within South America. When you click Start you will be shown a marker on a random populated South America grid square (courtesy of https://human-settlement.emergency.copernicus.eu/index.php). Also you will see an adjustable circle of radius 500 km to start. Adjust the circle’s radius by dragging it until it contains the target number of people shown – this target will be between 5 and 100 million people. Then click submit. You are scored on how close your circle’s population is to the target.