2022 · Q28
A car takes p minutes to travel a distance of 350 km with an average speed of u km/hr. Another car takes q minutes to travel the same distance with an average speed of v km/hr. If u - v = 5 and q - p = 140, then what is the value of u?
Elementary MathematicsTime, Speed and Distance
- A35
- B30
- C25
- D20
Explanation
With times in minutes, 21000/u-21000/v = -140 and u-v = 5. Thus 21000x5/(uv) = 140, so uv = 750 and u²-5u-750 = 0, giving u = 30 km/hr. Hence the keyed option is B.