A girl travels 30 km at a speed of 15 km/h. She travels another 20 km at a speed of 10 km/h. What is her average speed for the entire journey?
Answer & explanation
Correct answer: option 2
Average Speed = \(\frac{Total\; Distance }{Total\; Time }\)
Distance = Speed × Time
Total distance = 30 + 20 = 50 km
Total time = \(\frac{30 }{15 }\) + \(\frac{20 }{10 }\) = 4 hours
Average speed = \(\frac{50 }{4 }\) = 12.5 km/h