AbeNeedsAnswers wrote:Al and Ben are drivers for SD Trucking Company. One snowy day, Ben left SD at 8:00 a.m. heading east and Al left SD at 11:00 a.m. heading west. At a particular time later that day, the dispatcher retrieved data from SD's vehicle tracking system. The data showed that, up to that time, Al had averaged 40 miles per hour and Ben had averaged 20 miles per hour. It also showed that Al and Ben had driven a combined total of 240 miles. At what time did the dispatcher retrieve data from the vehicle tracking system?

A. 1:00 p.m.
B. 2:00 p.m.
C. 3:00 p.m.
D. 5:00 p.m.
E. 6:00 p.m.

B

Ben started at 8 am at an avg speed of 20 miles per hour

Al started at 11 am at an avg speed of 40 miles per hour

Thus, Ben started 3 hours earlier than Al

Therefore, the distance covered by Ben in 3 hours = 20 x 3 = 60 miles

Total distance covered by both Ben and Al = 240 miles

Total distance covered by Ben and Al after 11 am = 240 - 60 = 180 miles

Relative speed of Ben and AI = 20 + 40 = 60 miles per hour
Since Ben and Al are driving in opposite directions, their speeds would be added)

Time = Total distance / Relative speed

Time = 180/60 = 3 hours

Time when the dispatcher retrieved data = [spoiler]11:00 am + 3 hours = 2:00 pm.[/spoiler]

The correct answer: B

Hope this helps!

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Hi AbeNeedsAnswers,

This prompt gives us a lot of different facts about rates, times and distances, so we're clearly going to use the distance formula here:

Distance = (Rate)(Time)

We're looking for the time at which the distance between the two drivers was 240 miles - and since the answer choices are 5 times, we can use them 'against' the prompt and TEST THE ANSWERS.

Let's Test Answer B: 2:00pm
At 2pm....
Ben would have been driving for 6 hours at 20 miles/hour = 120 miles driven
Al would have been driving for 3 hours at 40 miles/hour = 120 miles driven
Total Distance = 120 miles + 120 miles = 240 miles
This is an exact MATCH for what we were told, so this MUST be the answer!

Final Answer: B

GMAT assassins aren't born, they're made,
Rich

AbeNeedsAnswers wrote:Al and Ben are drivers for SD Trucking Company. One snowy day, Ben left SD at 8:00 a.m. heading east and Al left SD at 11:00 a.m. heading west. At a particular time later that day, the dispatcher retrieved data from SD's vehicle tracking system. The data showed that, up to that time, Al had averaged 40 miles per hour and Ben had averaged 20 miles per hour. It also showed that Al and Ben had driven a combined total of 240 miles. At what time did the dispatcher retrieve data from the vehicle tracking system?

A. 1:00 p.m.
B. 2:00 p.m.
C. 3:00 p.m.
D. 5:00 p.m.
E. 6:00 p.m.

Let t represent the time passed between the departure of Al (11:00 a.m.) and the retrieval of data by the dispatcher. Since Ben left at 8 a.m., his time is (t + 3). Since they both traveled for a total 240 miles, we can use the formula distance = rate x time and create the following equation:

Ben's distance + Al's distance = 240

20(t + 3) + 40t = 240

20t + 60 + 40t = 240

60t = 180

t = 3 hours

Thus, it was 11 a.m. + 3 hours = 2 p.m. when the dispatcher retrieved data from the vehicle tracking system.

Answer: B