A person traveled 30% of a distance with a speed of 90 km/h and the remaining with a speed of 140 km/h . What is his average speed for the whole journey in km/h ?
Answer & explanation
Correct answer: option 4
Let the total distance = 100 km
30% of a distance = 30 km
Distance = Speed × Time
Total time = \(\frac{30}{90}\) + \(\frac{70}{140}\)
= \(\frac{5}{6}\)
Avg. speed = \(\frac{Total\;distance}{Total\;time\;taken}\)
Avg. speed = \(\frac{100}{\frac{5}{6}}\) = 120 km/h