Q35 of 168 Page 7

The speed of a boat in still water is 15 km/h. It can go 30 km upstream and return downstream to the original point in 4 hours and 30 minutes. Find the speed of the stream.

Let the speed of the boat be ‘X’ km/ hr, time taken for upstream and downstream be T1 hrs & T2 hrs respectively.



––––––– (i) (Downstream)


––––––– (ii) (Upstream)


Adding equation equation (i) & equation (ii),




2025 – 9X2 = 1800


9X2 = 225


X2 = 25


X = ±5


∵ speed can’t be negative.


∴ The speed of the stream be 5 Km/hr


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