A train running between two stations A and B arrives at its destination 10 minutes late when its speed is 50 km/h and 50 minutes late when its speed is 30 km/h. What is the distance between the stations A and B ? Choose the correct choice from the following.
A) 40 km	B) 50 km	C) 60 km	D) 70 km	E) None of these
Let the distance between the two stations be x km.   Then, x⁄50 - 10⁄60 = x⁄30 - 50⁄60   ⇒ x⁄50 - 1⁄6 = x⁄30 - 5⁄6   or x⁄30 - x⁄50 = 2⁄3 or x = 50 km   Answer 50 km
<result>B</result>
A train running between two stations A and B arrives at its destination 10 minutes late when its speed is 50 km/h and 50 minutes late when its speed is 30 km/h. What is the distance between the stations A and B ?