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Question: average speed Two youngsters were running as hard as they could. They averaged 6 miles per hour then had to rest for a while. On the way back they averaged 4 miles per hour for the exact same distance. Not counting the rest time, what was their average speed ? Answer: If you calculated the average by adding 6 and 4 equals 10, then divided 10 by 2 to get 5 mph .. that answer was wrong. The correct answer is actually 4.8 mph and this answer makes no difference with regard to total distance covered. For example: Using the given facts: 6 mph out and 4 mph back, let's use a distance that is easily divisible by 6 and 4 .. such as 12 miles. First divide 12 miles by 6 mph = 2; then divide 12 miles by 4 mph = 3. Now add 2 plus 3 = 5. Since the total distance traveled equals 24 miles which is 2 times 12, just divide 24 total miles by 5 and you get 4.8 mph. Just close this window to return to the logic questions. |
