Alex travels westward for 60 miles at an average speed of 30 miles per hour and then returns along the same route at an average speed of 90 miles per hour. What is his average speed for the entire trip?

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20 mph

45 mph

Correct

54 mph

60 mph

70 mph

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Explanation

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Official Explanation

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For the first leg of the journey, we calculate the time taken using the formula speed = distance/time. Thus, we have 30 = 60/t1, which gives t1 = 60/30 = 2 hours. For the return trip, we use the same formula: 90 = 60/t2, leading to t2 = 60/90 = 2/3 hours. The average speed for the…

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Comments

TeddyJan 28, 2025

Great explanation

SAug 5, 2024

Great

What this question tests

What it tests

Your application of distance = rate × time to trains, boats, and commuters, including relative speed.

Common trap

Mixing units (miles per hour vs. minutes) or averaging speeds — average speed is total distance over total time.