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i have a friend that lives in wichita, kansas. wichita is about 700 miles from rapid city. i sold him some tools and agreed that i would drive part of the way to wichita to deliver the tools. if he leaves at 9am (central standard time) and travels at an average speed of 69 mph, and i leave at 9am (mountain standard time) and travel at an average speed of 55 mph, how many hours will i drive before we meet?

User Matt Tabor
by
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1 Answer

4 votes

Answer:

5.09 hours (about 5 hours 5 minutes)

Explanation:

You want to know how many hours until you will meet your friend from Wichita if you drive 55 mph starting at 9 am Mountain time and he starts at 9 am Central time driving 69 mph. The distance between you is 700 miles at the start.

Time zones

Your friend's start time of 9 am Central time is 8 am Mountain time, so he has already driven 69 miles when you start. At that point in time, your separation is 700 -69 - 631 miles.

Closing speed

Once you're both on the road, the separation distance is being reduced at the rate of 55 +69 = 124 mph. At that rate, the separation distance of 631 miles will be covered in ...

time = distance/speed

time = (631 mi)/(125 mi/h) = 5.0887 h

You will drive about 5.09 hours before you meet.

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Additional comment

You will cover 279.9 miles before you meet. He will drive 6.09 hours and cover 420.1 miles before you meet.

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User Alagarasan M
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