Multiple choice

Two train start at the same time from two stations and proceed towards each other with speeds $40$ km per hour and $45$ km per hour respectively. When they meet, it is found that one train has travelled $40$ km more than other. Find the distance between the two stations.

  1. $360$ km
  2. $680$ km
  3. $720$ km
  4. $550$ km
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Relative speed = 40 + 45 = 85 km/h. Let time be t. Distance 1 = 40t, Distance 2 = 45t. 45t - 40t = 40. 5t = 40, t = 8 hours. Total distance = (40+45) * 8 = 85 * 8 = 680 km.

AI explanation

Using the relative speed method for trains moving towards each other, their relative speed is the sum of their individual speeds, giving 40 + 45 = 85 km/hr. The difference in their speeds is 45 - 40 = 5 km/hr, meaning the faster train gains 5 km over the slower one each hour. Since the total difference is 40 km, the time taken to meet is 40 divided by 5, which equals 8 hours. The total distance between the stations is their relative speed multiplied by the time, giving 85 multiplied by 8 = 680 km.