A train travels 120 km at a speed of 60 km/h and then 180 km at 90 km/h. What is the average speed for the entire journey? (2019)
Practice Questions
1 question
Q1
A train travels 120 km at a speed of 60 km/h and then 180 km at 90 km/h. What is the average speed for the entire journey? (2019)
72 km/h
75 km/h
80 km/h
85 km/h
Total time = (120/60) + (180/90) = 2 + 2 = 4 hours. Total distance = 120 + 180 = 300 km. Average speed = Total distance / Total time = 300/4 = 75 km/h.
Questions & Step-by-step Solutions
1 item
Q
Q: A train travels 120 km at a speed of 60 km/h and then 180 km at 90 km/h. What is the average speed for the entire journey? (2019)
Solution: Total time = (120/60) + (180/90) = 2 + 2 = 4 hours. Total distance = 120 + 180 = 300 km. Average speed = Total distance / Total time = 300/4 = 75 km/h.
Steps: 8
Step 1: Calculate the time taken to travel the first part of the journey (120 km at 60 km/h). Use the formula: time = distance / speed.
Step 2: For the first part, time = 120 km / 60 km/h = 2 hours.
Step 3: Calculate the time taken to travel the second part of the journey (180 km at 90 km/h).
Step 4: For the second part, time = 180 km / 90 km/h = 2 hours.
Step 5: Add the time taken for both parts to find the total time: Total time = 2 hours + 2 hours = 4 hours.
Step 6: Calculate the total distance traveled: Total distance = 120 km + 180 km = 300 km.
Step 7: Calculate the average speed using the formula: average speed = total distance / total time.
Step 8: Average speed = 300 km / 4 hours = 75 km/h.
