2017 · Q93
A man travelled 12 km at a speed of 4 km/hr and further 10 km at a speed of 5 km/hr. What was his average speed ?
Elementary MathematicsTime, Speed and Distance
- A4.4 km/hr
- B4.5 km/hr
- C5.0 km/hr
- D2.5 km/hr
Explanation
Total distance 22 km; total time = 12/4+10/5 = 3+2 = 5 h. Average speed = 22/5 = 4.4 km/h. Hence option (A) 4.4 km/hr. (Trap: the plain mean of 4 and 5 is 4.5, but time-weighting is needed.)