SOLUTION: A person drove for 6 hours at an average speed of 45 miles per hour and for 9 hours at an average speed of 55 mph. Find the average speed for the entire trip. (I tried 45/6 + 55/
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Question 651287: A person drove for 6 hours at an average speed of 45 miles per hour and for 9 hours at an average speed of 55 mph. Find the average speed for the entire trip. (I tried 45/6 + 55/9 =100/15. 15 divided into 100 = 66...is answer 66 mph? Don't think so.) Answer by MathTherapy(10559) (Show Source):
You can put this solution on YOUR website!
A person drove for 6 hours at an average speed of 45 miles per hour and for 9 hours at an average speed of 55 mph. Find the average speed for the entire trip. (I tried 45/6 + 55/9 =100/15. 15 divided into 100 = 66...is answer 66 mph? Don't think so.)
Wrong, wrong, wrong approach!! You're right....it's not so, at all. See below!!
Distance covered at 45 mph for 6 hours = 45 * 6, or 270 miles
Distance covered at 55 mph for 9 hours = 55 * 9, or 495 miles
Total distance traveled = 270 + 495, or 765 miles
Total time taken to travel 765 miles = 6 + 9, or 15 hours
Average speed = total distance, divided by total time
Average speed for entire trip = , or mph
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