A car driver takes a total of two hours to make a journey of 75km. During the journey, she takes a break of half an hour and spends a quarter of an hour stationary in a traffic jam. At what average speed must she travel during the rest of the time for the whole journey to take two hours?
How to solve this question:
Basic formula :
Average Speed = Distance/ time
Total time that the driver is stationary = 0.5 hr (break time) + 0.25 hr (stuck in jam) = 0.75 hr
The time that the driver has to reach her destination = 2hr – 0.75hr = 1.25hr
Since the distance is 75km, and putting these numbers into the above formula:
Average Speed = 75km/1.25hr = 60 km/hr