2016 · Q43
A and B run a 1 km race. A gives B a start of 50 m and still beats him by 15 seconds. If A runs at 8 km/h, what is the speed of B?
General Mental Ability, Quantitative Aptitude and StatisticsTime, work and measurement
- A4.4 km/h
- B5.4 km/h
- C6.4 km/h
- D7.4 km/h
Explanation
A’s speed is 8 km/h = 20/9 m/s, so A covers 1000 m in 450 s. B covers 950 m (the 50 m start) in 450 + 15 = 465 s, i.e. 950/465 m/s ≈ 2.043 m/s = 7.35 km/h ≈ 7.4 km/h. Hence (D).