Final answer:
The total displacement of the car is 16.2 miles north.
Step-by-step explanation:
The total displacement of the car can be found by adding the individual displacements together. The first segment of the car's travel is 3.9 miles north, which gives a displacement of 3.9 miles north. The second segment is 12.3 miles north, which gives a displacement of 12.3 miles north. Adding these together, the total displacement is 3.9 + 12.3 = 16.2 miles north. Therefore, the correct option is (a) 16.2 mi north.
The total displacement of a car that travels 3.9 miles north and then 12.3 miles north is the sum of both displacements, because they are in the same direction. To find the total displacement, you simply add the two distances together.
3.9 miles north + 12.3 miles north = 16.2 miles north
Thus, the total displacement is 16.2 miles north, which corresponds to option (a).