1. Two trains start from P and Q respectively and travel towards each other at a speed of 30 km/hr and 20 km/hr respectively. By the time they meet, the first train has travelled 50 km more than the second. The distance between P and Q is:
Solution:
Let the distance travelled by 2nd train be x and the 1st train be x+50
x/20 = (x+50)/30
30x = 20x+1000
x = 100.
Distance between them = x+x+50 = 250 km.
2. The distance between 2 cities A and B is 220 km. A train starts from A at 10 AM and travels towards B at 50 km/hr. Another train starts from B at 11 AM and travels towards A at 70 km/hr. At what time do they meet?
Solution:
Consider they meet x hours after 10 AM
50x+70(x-1) = 220
By solving above equation, we get
x =29/12 = 2(5/12) = 2 hours 25 minutes.
They meet at 12.25 PM. (10 AM + 2 hours 25 minutes)
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