Question 1160583
i get the following.
traffic jam is 4 miles.
that would be 4 * 5280 = 21120 feet.
the average length of a car is 13.5 feet and the average length of a truck is 20 feet.
allow 3 feet in front of each and the average length of a car is 16.5 feet and the average length of a truck is 23 feet.
70% of the traffic is cars and 30% of the traffic is trucks.
i take this to mean that 70% of the traffic is composed of cars and 30% of the traffic is composed of trucks.
this should mean that the average length of a vehicle will be 70% * 16.5 feet plus 30% * 23 feet = 18.45 feet.
divide 21120 total feet by 18.45 feet average length of a vehicle and you get approximately 1144.715447 vehicles.
this is not one of the selections but it's close enough o 1172 to make that the most likely answer.
i also looked at it another way which i don't think is right, but it does give you one of the selections.
total feet is 4 * 5280 = 21120
if you assume 70% of the traffic is cars, and you multiply 21120 by .7, you get 14784 feet of cars and 6336 feet of trucks.
14784 / 16.5 average length of a car = 896 cars.
6336 / 23 average length of a truck = 276 trucks founded to the next highest integer.
total vehicles is therefore 1172.
i believe traffic means vehicles and not length of vehicles, so i think my first analysis is more accurate, but this is a matter of interpretation.
either way, the selection of 1172 appears to be most accurate, so i think you're ok with selection C.