Question

Correct answers only please!

On a residential single lane road there was a wreck that backed up traffic for 5 miles. 80% of the traffic consists of cars and 20% of the traffic consists of trucks. The average distance between vehicles is 3 feet. The average length of a car is 13.5 feet and the average length of a truck is 20 feet. Estimate how many vehicles are stuck in the traffic jam.

(Hint: There are 5280 feet in 1 mile.)

A. 853 vehicles

B. 1510 vehicles

C. 2103 vehicles

D. 2320 vehicles

Answer 1

B. 1510

Explanation:

Cars: 21120 ft (4mi) , 16.5

Trucks: 5280 ft (1mi) , 23

21120/16.5 = 1280 cars

5280/23 = 229.5 trucks

1509.5 so 1510 is the answer

Answer 2

Option B.

Explanation:

Length of the traffic has been given as 5 miles or 26400 feet (5×5280)

Let the number of cars in the traffic = x

Since average length of the car = 13.5 feet

So, length of traffic because of cars = 13.5x feet

Distance between the vehicle = 3 feet

Distance between x cars = 3x feet

Length of the traffic by cars = 80% of 26400

= 21120 feet

Therefore, length of the traffic by cars = length of cars + distance between them

21120 = 13.5x + 3x

21120 = 13.5x + 3x

21120 = 16.5x

16.5x = 21120

x = 1280 cars

Let the number of trucks in the traffic = y

Length of each truck = 20 feet

Length of the traffic by the trucks = 20y feet

Distance between the trucks = 3y feet

Total length by trucks = 20y + 3y = 23y

Since length of the traffic by trucks is = 20% of 26400

= 5280 feet

Therefore, 5280 = 23y

y =
`(5280)/(23)`

y = 230

Total number of vehicles = x + y = 1280 + 230

= 1510

Option B is the answer.