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Question

Difficulty: MediumAverage Speed

Fill in the blank with the correct numeric value.

Answer:A military dispatch rider travels 7575 miles on a highway in 11 hour and 3030 minutes. He then travels an additional 2525 miles on secondary roads in 11 hour. The rider's average speed for the entire trip is 【40】 miles per hour.

Answer

The average speed for the entire trip is 40 miles per hour.
The correct average speed is found by dividing the total distance (100100 miles) by the total travel time (2.52.5 hours), which results in exactly 4040 miles per hour.

Step-by-Step Solution

1
Calculate the total distance traveled.
75+25=10075 + 25 = 100 miles.
Average speed calculation requires the total distance of the trip.
2
Convert all time measurements to hours and calculate the total time.
11 hour and 3030 minutes is equivalent to 1.51.5 hours. Total time =1.5+1=2.5= 1.5 + 1 = 2.5 hours.
The requested rate is in miles per hour, so the total time must be consistently represented in hours.
3
Divide the total distance by the total time to find the average speed.
100÷2.5=40100 \div 2.5 = 40 miles per hour.
The fundamental formula for average speed is Total Distance÷Total Time\text{Total Distance} \div \text{Total Time}.

Key Concept

Average speed is calculated by dividing the total distance traveled by the total time taken for the trip, not by taking the arithmetic mean of the individual segment speeds.
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Average Speed

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