The ratio of the speed of two trains is 7:8. If the second train runs 400 km in 4 hours, what is the speed of the first train?

दूसरी ट्रेन की गति = 400/4 = 100 किमी/घंटा। 8 इकाइयाँ = 100 implies 1 इकाई = 12.5। पहली ट्रेन की गति = 7 * 12.5 = 87.5 किमी/घंटा।