A train running at a steady speed overtakes two men who are walking along the track ahead of it at 4 km/h and 8 km/h, passing them completely in 9 seconds and 10 seconds respectively. The length of the train (in metres) is:

Question

Accepted Answer

100. With the train at v km/h, its length is 9(v − 4)(5/18) = 10(v − 8)(5/18) metres. So 45(v − 4) = 50(v − 8), giving v = 44 km/h and length = 2.5 × 40 = 100 m (check: 10 × (25/9) × 36/10 = 100 m too). Treating the men as though they were standing still gives 44 × (5/18) × 9 = 110 m — it is the train's speed RELATIVE to a walking man that matters.

A train running at a steady speed overtakes two men who are walking along the track ahead of it at 4 km/h and 8 km/h, passing them completely in 9 seconds and 10 seconds respectively. The length of the train (in metres) is:

Step-by-Step Solution

Master this topic in 30 minutes a day.

More Ratio, Percentage & Commercial Math practice