Speed & Time: A motorist drives..

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Speed & Time: A motorist drives..

by euro » Fri Oct 08, 2010 5:38 am
[Q] A motorist drives from Miami to Dallas, a distance of approximately 1300 miles, at an average rate of 65 miles per hour. If the motorist arrives in Dallas at 11:30 in the evening, and if the time in Dallas is one hour earlier than the time in Miami, at what time did the motorist leave Miami?

(A) 2:30 a.m.

(B) 3:30 a.m.

(C) 4:30 a.m.

(D) 5:30 a.m.

(E) 6:30 a.m.

OA [spoiler] (C) [/spoiler]

Even though the problem looks simple, the language is confusing. Any comments?

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by deepak123gmat » Fri Oct 08, 2010 5:56 am
If the time in Dallas is one hour earlier than the time in Miami then the motorist reaches 12.30 Dallas time.
Now, at an average rate of 65 miles per hour it takes 20 hours to cover 1300 miles.
Just go 20 hours back in time and you will get 4.30 a.m. (c)

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by deepak123gmat » Fri Oct 08, 2010 6:04 am
Sorry, i meant to say 12.30 Miami time.

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by GMATGuruNY » Fri Oct 08, 2010 6:33 am
euro wrote:[Q] A motorist drives from Miami to Dallas, a distance of approximately 1300 miles, at an average rate of 65 miles per hour. If the motorist arrives in Dallas at 11:30 in the evening, and if the time in Dallas is one hour earlier than the time in Miami, at what time did the motorist leave Miami?

(A) 2:30 a.m.

(B) 3:30 a.m.

(C) 4:30 a.m.

(D) 5:30 a.m.

(E) 6:30 a.m.

OA [spoiler] (C) [/spoiler]

Even though the problem looks simple, the language is confusing. Any comments?
Total travel time = d/r = 1300/65 = 20 hours.

Safest approach would be to plug in the answer choices, which represent the time the motorist left Miami. We should start with C, the answer choice right in the middle:

Leave at 4:30am
4:30am + 20 hours = 12:30am
One hour earlier is 11:30pm. Success!

The correct answer is C.
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