2017 · Q13
In a 100 m race, A runs at 6 km/hr. If A gives B a start of 8 m and still beats him by 9 seconds, what is the speed of B ?
Elementary MathematicsTime, Speed and Distance
- A4.6 km/hr
- B4.8 km/hr
- C5.2 km/hr
- D5.4 km/hr
Explanation
A runs 100 m at 6 km/h = 5/3 m/s, taking 60 s. B runs 100−8 = 92 m in 60+9 = 69 s, so B's speed = 92/69 m/s = 4/3 m/s. Converting to km/h: (4/3)×3.6 = 4.8 km/h. Hence option (B) 4.8 km/hr.