My question is: Some friends went hiking for 3.5 hours. They traveled 21 kilometers in that time. Birgit was 4 minutes/km faster than the average time. If Birgit kept the same pace, how many minutes would it take her to go 8 kilometers? Your thoughts:
Minutes spent hiking = 3.5 * 60 = 210 minutes. Average speed = 210 minutes / 21 km = 10 minutes / km. Birgit is 4 minutes / km faster = 10 - 4 = 6 min / km. It would take 6 * 8 = 48 minutes to go 8 km. Birgit would take 48 minutes to travel 8 kilometers. The final answer: 48.