Multiple choice

Stations X, Y, Z, and W are situated on the same route. The distances from station X to stations Y, Z and W are 150 km, 250 km and 350 km, respectively. Trains A and B depart from X simultaneously on parallel tracks, heading towards W. At the same time, train C departs from W and travels towards X. Train C crosses train A at station Z and train B at station Y. Assuming each train maintains a constant speed, what is the ratio of the speed of train B to that of train A?

  1. 3 : 10

  2. 7 : 10

  3. 3 : 4

  4. 10 : 3
Reveal answer Fill a bubble to check yourself
A Correct answer
AI explanation

Assuming the speeds of trains A, B, and C are Sa, Sb, and Sc, respectively, the time taken for train A and train C to meet at station Z is 250 divided by Sa, which equals 350 divided by Sc. This means the ratio of the speed of train C to train A is 7 to 5. The time taken for train B and train C to meet at station Y is 150 divided by Sb, which equals 350 divided by Sc. This means the ratio of the speed of train C to train B is 7 to 3. By equating the two expressions for the speed of train C, we find that 7/5 multiplied by Sa equals 7/3 multiplied by Sb. Solving this relationship gives the ratio of the speed of train B to train A as 3 to 10.

Keep practicing — related questions