A FERRY BOAT TRAVELS BETWEEN 2 POINTS A,B ON OPPOSITE BANKS OF A RIVER distance between ab is1200m

Question

the velocity of stream=1.9,AB makes 60degrees with stream.Atwhat angle and velocity should it move to cover AB and back in 5 seconds. {its my life and death question please help}

Answer 1

Dist. between 2 banks of stream=1200mts

Length of path AB=800*3^1/2

Total time for going to opposite bank & come back=5s

Time for going to opposite bank=2.5 s   [assuming the ferry travels at const.speed]

Velocity of ferry=320*(3^1/2) m/s