2016 · Q12
Two men, A and B run a 4 km race on a course 0.25 km round. If their speeds are in the ratio 5 : 4, how often does the winner pass the other ?
Elementary MathematicsTime, Speed and Distance
- AOnce
- BTwice
- CThrice
- DFour times
Explanation
The 4 km race is 16 laps of 0.25 km. In the winner's time the slower runner covers 4×4/5 = 3.2 km, so the winner gains 0.8 km = 3.2 laps on him. Each full lap gained is one passing, and the gain crosses the 1-, 2- and 3-lap marks — three passings (option C).