Question

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
$N=\frac{20Ld}{600+s^2}$
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 $\frac{1}{2}$ 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)

• A. 155
• B. 96
• C. 80
• D. 48
• E. 24

Answer 1

The correct option is D 48

So, we make use of the given formula:

d is the length of portion of highway in feet

So, 1/2 mile = 5280/2 = 2640 feet.

N= $\frac{20\times 2\times 2640}{600+{40}^2}$

$\to$ N = 48