Error in book? Please confirm.

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Discussion Overview

The discussion revolves around a problem involving the relative motion of a train and a car traveling parallel to each other. Participants analyze the scenario to determine when the car will pass the train, considering their respective speeds and the time difference in their departures.

Discussion Character

  • Homework-related
  • Mathematical reasoning

Main Points Raised

  • One participant calculates that the train is 13 miles ahead of the car when the car starts, based on the train's speed and the 15-minute delay in the car's departure.
  • The same participant determines that the car and train are converging at a rate of 12 mph and calculates the time it takes for the car to catch up to the train as 65 minutes.
  • Another participant points out that adding 65 minutes to the car's start time of 5:15 results in 6:20, suggesting an error in the initial calculation.
  • There is a light-hearted exchange about using a graphing calculator to arrive at the correct answer, indicating a casual tone among participants.

Areas of Agreement / Disagreement

Participants acknowledge an error in the initial calculation regarding the time the car passes the train, with a consensus on the corrected time being 6:20. However, the initial confusion and the calculation process remain part of the discussion.

Contextual Notes

The discussion highlights the importance of careful arithmetic in solving relative motion problems, as well as the potential for simple mistakes in calculations.

Holocene
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A highway and a train track run parallel to each other. At 5:00 a train crosses a river. Fifteen minutes later, a car, traveling in the same dirrection, crosses the river. The train's average speed is 52mph, the car's is 64mph. When will the car pass the train?

15 minutes = 1/4hour, so train traveling 52mph is 13 miles away from the car over the river.

64 - 52 = The vehicles are converging at a rate of 12mph.

From D = RT, T = D/R. So,

T = 13/12

13/12 = 1 and 1/12th of an hour, or 65 minutes.

The car should pass the train in 01:05, or at 6:05.

This answer is not listed among the choices.

WTF?
 
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5:15 + 65 mins. = 6:20...
 
and also, i can't help myself, maybe you would've gotten 6:20 with a graphing calculator :)

jk. although i do love my ti83
 
matticus said:
5:15 + 65 mins. = 6:20...

wow, what a dumb error on my part.

Thanks.
 
matticus said:
and also, i can't help myself, maybe you would've gotten 6:20 with a graphing calculator :)

jk. although i do love my ti83


haha, thanks.
 

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