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Andrew drove from A to B at 60 miles per hour. Then he realized that h
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27 Feb 2023, 02:57
27 Feb 2023, 02:57
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Andrew drove from A to B at 60 miles per hour. Then he realized that he forgot something at A, and drove back at 80 miles per hour. He then zipped back to B at 90 mph. What was his approximate average speed in miles per hour for the entire trip?
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74.5
Re: Andrew drove from A to B at 60 miles per hour. Then he realized that h
[#permalink]
18 Mar 2023, 03:13
18 Mar 2023, 03:13
Expert Reply
OE
Use a Multiple RTD chart to solve this problem. Start by selecting a Smart Number for d, such as 720 miles. (This is a common multiple of the 3 rates in the problem.) Then work backward to find the time for each trip and the total time:
Ta=720/60=12 hrs
Tb=720/80=9 hrs
Tc=720/90=8 hrs
T= 29 hrs
Average speed\(=\frac{2,160}{29} \approx 74.5\) miles per hr
Use a Multiple RTD chart to solve this problem. Start by selecting a Smart Number for d, such as 720 miles. (This is a common multiple of the 3 rates in the problem.) Then work backward to find the time for each trip and the total time:
Ta=720/60=12 hrs
Tb=720/80=9 hrs
Tc=720/90=8 hrs
T= 29 hrs
Average speed\(=\frac{2,160}{29} \approx 74.5\) miles per hr
gmatclubot
Re: Andrew drove from A to B at 60 miles per hour. Then he realized that h [#permalink]
18 Mar 2023, 03:13
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