Question

A car at a constant speed of 50km/h for 100km then speeds up to 100km/h and drives another 100km. What is the car's average speed for the 200km trip?

A) 66.7 km/h
B) 75 km/h
C) 80 km/h
D) 90 km/h

Answer 1

The average speed of the car for the 200km trip, considering the speeds of 50km/h for the first 100km and 100km/h for the next 100km, is calculated by dividing the total distance by the total time taken, which results in an average speed of 66.7 km/h.

Step-by-step explanation:

To find the average speed of the car for the entire trip, we need to divide the total distance traveled by the total time taken for the trip. The car travels at 50km/h for the first 100km and then 100km/h for the next 100km. Let's find the time taken for each segment of the trip first.

For the first 100km at 50km/h:
Time = Distance / Speed = 100km / 50km/h = 2 hours

For the next 100km at 100km/h:
Time = Distance / Speed = 100km / 100km/h = 1 hour

The total time taken for the trip is 2 hours + 1 hour = 3 hours. The total distance is 100km + 100km = 200km.

Now, calculate the average speed using the formula:
Vavg = Total distance / Total time = 200km / 3h = 66.7 km/h

Therefore, the correct answer is A) 66.7 km/h.