2019 · Q5
Three cars A, B and C started from a point at 5 p.m., 6 p.m. and 7 p.m. respectively and travelled at uniform speeds of 60 km/hr, 80 km/hr and x km/hr respectively in the same direction. If all the three met at another point at the same instant during their journey, then what is the value of x?
Elementary MathematicsTime, Speed and Distance
- A120
- B110
- C105
- D100
Explanation
Let the meeting be t hours after 5 p.m. and D km away. 60t = D and 80(t−1) = D give 60t = 80t − 80, so t = 4 h and D = 240 km. Car C travels for 2 h, so x × 2 = 240 and x = 120 km/h.