There is a river beside a road. Kiran and Varun started from a place P, moved to a shop situated at another place Q and then returned to P again. Kiran moves on a cycle at a speed of 14 km/hr, while Varun sails on a boat at a speed of 9 km/hr. if the river flows at the speed of 3 km/hr, which of the two boys will return to place P first ?
Kiran moves both ways at a speed of 14 km/hr.
so, average speed of the Kiran = (2*14*14)/(14+14) = 14 km/hr.
Varun moves downstream at (9 +3) = 12 km/hr and upstream at (9 -3) = 6 km/hr.
so, the average speed of the Varun = (2*12*6)/(12+6) = 8 km/hr.
hence, Kiran will return to P first.
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