A train leaves station X at 5 a.m. and reaches station Y at 9a.m. Anot

1.	A train leaves station X at 5 a.m. and reaches station Y at 9a.m. Another train leaves station Y at 7 a.m. and reachesstation X at 10: 30 a.m. At what time do the two trains crosseach other ?(a) 7:36 am(c) 8:36 am(b) 7:56 am(d) 8:56 am
Answer» Time taken by train 1 from x to y = 4 hours It travels for 2 hours before train 2 starts. Time taken by train 2 from y to x = 3.5 hours Let distance between x & y = LCM(4,3.5) = 28 kms Speed of Train 1 = 28/4 = 7 kmph Speed of Train 2 = 28/3.5 = 8 kmph Train 1 covers 7 x 2 = 14 km by the time Train 2 starts at 7 AM. So, distance between the two trains at 7 AM is 28 - 14 = 14km Relative speed = 7 + 8 = 15 kmph Time taken to cross each other = 14/15 hours or 56 minutes. => They meet at 7:56 AM. (b) is correct option.

A train leaves station X at 5 a.m. and reaches station Y at 9a.m. Another train leaves station Y at 7 a.m. and reachesstation X at 10: 30 a.m. At what time do the two trains crosseach other ?(a) 7:36 am(c) 8:36 am(b) 7:56 am(d) 8:56 am

Answer»

Time taken by train 1 from x to y = 4 hours

It travels for 2 hours before train 2 starts.

Time taken by train 2 from y to x = 3.5 hours

Let distance between x & y = LCM(4,3.5) = 28 kms

Speed of Train 1 = 28/4 = 7 kmph

Speed of Train 2 = 28/3.5 = 8 kmph

Train 1 covers 7 x 2 = 14 km by the time Train 2 starts at 7 AM.

So, distance between the two trains at 7 AM is 28 - 14 = 14km

Relative speed = 7 + 8 = 15 kmph

Time taken to cross each other = 14/15 hours or 56 minutes.

=> They meet at 7:56 AM.

(b) is correct option.