Two trains, one from Howrah to Patna and the other from Patna to Howrah, start simultaneously. After they meet, the trains reach their destinations after 49 hours and 25 hours respectively. The ratio of their speeds is?
Choices:	A) 4 : 9	B) 5 : 7	C) 4 : 5	D) 4 : 1	E) 4 : 2

Rationale: "let us name the trains a and b . then , ( a ' s speed ) : ( b ' s speed ) = √ b : √ a = √ 25 : √ 49 = 5 : 7 answer : b"
Answer: B