Scientists have determined that the average time for intercourse is 4 minutes. The average number of strokes per minute is 9, and since the average length is 6 inches, the average girl recieves 216 inches, or 18 feet, per intercourse. The average girl does it about 3 times a week, 50 weeks of the year, and 150 times 18 makes 2700 feet, or just a little over half a mile.