IIMB 2001 (QA) PYQs

A train leaves station A towards station B at 60 km/h. Another train leaves station B towards station A at 90 km/h. The distance between stations A and B is 300 km. If both trains leave their respective stations at the same time, and a bird starts flying from train A to train B at a speed of 120 km/h when the trains start, and immediately turns back to train A upon reaching train B, continuing this back-and-forth flight until the trains meet, what is the total distance the bird will have flown by the time the trains meet?

Ash Ketchum on a journey completed his travels using two modes of transport: walking and riding a bicycle. Ash walked a total of 90 km and rode the bicycle for 10 km. The time he spent riding the bicycle was four hours less than the time he spent walking. If the times spent on each mode of transport were swapped, the distances covered by walking and riding would be equal. How long did Ash spend riding the bicycle?

Sam paddles upstream for $2$ hours, covering a distance of $10$ km. Then, he paddles downstream for $1.5$ hours, covering a distance of $12$ km. Determine the speed of the current.