A car travels the first 150 km of a trip at 60 km/h and the remaining 100 km at 80 km/h. What is the car’s average speed for the entire trip?
["# What’s the Average Speed for a Journey That Combines Two Speed Zones?", "When planning a long car trip, understanding average speed is crucial—not just for estimating arrival times, but also for optimizing route efficiency. Consider this common scenario: a 150 km stretch driven at 60 km/h followed by the final 100 km traveled at 80 km/h. What is the car’s true average speed over the entire 250 km journey? Let’s break it down step by step to uncover the answer.", "## Understanding Average Speed: More Than Just a Mean", "Average speed is not simply the total distance divided by total time. Instead, it’s calculated as:", "[\n\ ext{Average Speed} = \frac{\ ext{Total Distance}}{\ ext{Total Time}}\n]", "Using only a rough average of the two speeds (i.e., ( \frac{60 + 80}{2} = 70 ) km/h) would mislead. To find the actual average, we must first compute the total time taken for each segment and then combine them.", "---", "## Step-by-Step Calculation", "Segment 1: 150 km at 60 km/h\n[\n\ ext{Time}_1 = \frac{\ ext{Distance}_1}{\ ext{Speed}_1} = \frac{150\ \ ext{km}}{60\ \ ext{km/h}} = 2.5\ \ ext{hours}\n]", "Segment 2: 100 km at 80 km/h\n[\n\ ext{Time}_2 = \frac{\ ext{Distance}_2}{\ ext{Speed}_2} = \frac{100\ \ ext{km}}{80\ \ ext{km/h}} = 1.25\ \ ext{hours}\n]", "---", "## Total Time and Average Speed", "Now, sum the distances and times:\n[\n\ ext{Total Distance} = 150\ \ ext{km} + 100\ \ ext{km} = 250\ \ ext{km}\n]\n[\n\ ext{Total Time} = 2.5\ \ ext{h} + 1.25\ \ ext{h} = 3.75\ \ ext{hours}\n]", "Now calculate the average speed:\n[\n\ ext{Average Speed} = \frac{250\ \ ext{km}}{3.75\ \ ext{h}} = \boxed{66.\overline{6}\ \ ext{km/h} \approx 66.7\ \ ext{km/h}\n]", "---", "## Why This Matters When Planning Trips", "Knowing the true average speed helps travelers set realistic timelines. While the uneven driving speeds might lead drivers to assume a faster journey, the real average reflects the slower segment’s influence. Understanding this principle can improve route planning, especially in mixed-traffic or varied terrain conditions.", "---", "## Final Thoughts", "For a trip covering 250 km with segments at 60 km/h and 80 km/h, the average speed is exactly 66.7 km/h. This example illustrates that average speed rewards careful attention to both time and distance, offering a reliable metric over simple speed averaging.", "Whether you’re commuting, embarking on a road trip, or designing delivery routes, mastering average speed calculations empowers smarter decisions and smoother travel planning.", "---", "Keywords: average speed calculation, travel speed comparison, car trip average speed, 60km/h to 80km/h journey, road trip time and distance, how to calculate average speed, mixed speed journey average speed.\nMeta Description: Discover the accurate average speed for a car trip that first travels 150 km at 60 km/h and then 100 km at 80 km/h — with step-by-step calculation and practical travel insights."]
