Source: Official Guide for the GMAT 12th Ed. Section 5.3 Problem Solving; #68

2

At a certain instant in time, the number

At a certain instant in time, the number of cars, N, traveling on a portion of a certain highway can be estimated by the formula N=20Ld/(600+ s) where L is the number of lanes in the same direction, d is the length of the portion of the highway, in feet, and s is the average speed of the cars, in miles per hour. Based on the formula, what is the estimated number of cars traveling on a 1/2-mile -portion of the highway if the highway has 2 lanes in the same direction and the average speed of the cars is 40 miles per hour? (5,280 feet = 1 mile) 155, 96, 80, 48, 24

2 Explanations

1

Tushant mathur

shouldn't we convert s=40 miles in feet because "d" is also in feet.

Oct 28, 2017 • Comment

Jonathan , Magoosh Tutor

Hi Tushant,
No, we should not convert, because the formula specifically has "s" as the speed in miles per hour.

Nov 6, 2017 • Reply

2

Gravatar Mike McGarry, Magoosh Tutor

Nov 5, 2012 • Comment

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Section 5.3 Problem Solving

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