Two cities, Delhi and Jaipur, are 360 km apart. A car goes from Delhi to Jaipur at a speed of 80 km/h and returns to Delhi from Jaipur using the same route at a speed of 120 km/h. What is the average speed of the car?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 96 km/h
We can use the formula for average speed, which is:
average speed = total distance / total time
Let's first find the total distance traveled by car, which is the sum of the distances traveled from Delhi to Jaipur and from Jaipur to Delhi:
total distance = distance from Delhi to Jaipur + distance from Jaipur to Delhi
total distance = 360 km + 360 km
total distance = 720 km
Now, let's find the total time taken by the car. We can use the formula:
time = distance/speed
For the trip from Delhi to Jaipur:
time from Delhi to Jaipur = distance / speed
time from Delhi to Jaipur = 360 km / 80 km/h
time from Delhi to Jaipur = 4.5 hours
For the return trip from Jaipur to Delhi:
time from Jaipur to Delhi = distance / speed
time from Jaipur to Delhi = 360 km / 120 km/h
time from Jaipur to Delhi = 3 hours
The total time taken by the car is the sum of the time taken for the two trips:
total time = time from Delhi to Jaipur + time from Jaipur to Delhi
total time = 4.5 hours + 3 hours
total time = 7.5 hours
Now we can find the average speed using the formula:
average speed = total distance / total time
average speed = 720 km / 7.5 hours
average speed = 96 km/h
Therefore, the average speed of the car is 96 km/h.