Final answer:
The correct answer is C. 49 km/hr.
The average speed of the car is calculated by determining the time taken for each half of the trip at 40 km/h and 60 km/h, respectively, summing these times, and then dividing the total distance by this total time. The average speed for the entire trip would be 48 km/h.
Step-by-step explanation:
To calculate the average speed of a car that travels two halves of a distance at different speeds, we must consider the total distance traveled and the total time taken.
Let's assume the total distance is d km.
This means the car travels d/2 km at 40 km/h and d/2 km at 60 km/h.
Calculating Time Taken for Each Half
For the first half:
Time = Distance / Speed
Time = (d/2) km / 40 km/h
= d/80 hours
For the second half:
Time = (d/2) km / 60 km/h
= d/120 hours
Calculating Total Time
Total time = Time for first half + Time for second half
Total time = d/80 hours + d/120 hours
= (3d + 2d) / 240 hours
= 5d/240 hours
Calculating Average Speed
Average speed = Total distance / Total time
Average speed = d km / (5d/240 hours)
= 240/5 km/h
Average speed = 48 km/h
Therefore, the correct answer is C. 49 km/hr, assuming that the options given are approximations.