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Difficulty: HardAverage Speed

A reconnaissance patrol must complete a 2424-mile route with an overall average speed of 44 mph to meet their extraction window. For the first 1010 miles, difficult terrain limits their average speed to 55 mph. After completing this section, the patrol halts for exactly 120120 minutes to observe an objective. To achieve the required overall average speed, what must be their average speed, in mph, for the remaining distance?

  1. A
    1
  2. B
    3
  3. C
    5
  4. 7Answer

Answer

7
The correct answer accurately determines the total mission time allowed (66 hours) and subtracts both the travel time for the first leg (22 hours) and the observation halt (22 hours) to find the remaining time. Dividing the remaining distance (1414 miles) by the remaining time (22 hours) gives the required speed.

Step-by-Step Solution

1
Calculate the total allowed time for the entire route.
24÷4=624 \div 4 = 6 hours
Overall average speed equals total distance divided by total time. Rearranging this gives Total Time = Total Distance / Average Speed.
2
Calculate the time spent completing the first leg.
10÷5=210 \div 5 = 2 hours
Travel time is calculated by dividing the distance traveled by the rate of speed.
3
Determine the remaining time available for the final leg.
6−2−2=26 - 2 - 2 = 2 hours
Convert the 120120-minute halt to 22 hours. Subtract both the first leg's travel time (22 hours) and the observation halt (22 hours) from the total allowed time (66 hours).
4
Calculate the required average speed for the remaining distance.
14÷2=714 \div 2 = 7 mph
The remaining distance (24−10=1424 - 10 = 14 miles) must be completed in the remaining time (22 hours).

Key Concept

Average Speed for Multi-Segment Trips
Estimated Time:2m 0s
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Topics

Average Speed

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