2022 · Q36
A person X starts from a place A and another person Y starts simultaneously from another place B which is d km away from A. They walk in the same direction. X walks at an average speed of u km/hr and Y walks at an average speed of v km/hr. How far will X have walked before he overtakes Y?
Elementary MathematicsTime, Speed and Distance
- Aud/(u-v)
- Bvd/(u-v)
- C(ud-vd)/(u-v)
- D(ud-vd)/(u+v)
Explanation
X closes the d km gap at relative speed (u−v) km/h, so overtaking takes d/(u−v) hours, during which X walks u·d/(u−v) km. The distractor vd/(u−v) is the distance the slower walker Y covers in that time, not X. The keyed option is A.