A train takes 20 seconds to cross a pole. It takes 50 seconds to cross the platform. What is the ratio of the length of the platform to that of the train?
ক
2 : 3
খ
2 : 5
গ
5 : 2
ঘ
3 : 2
ঙ
None
সঠিক উত্তর: 3 : 2