Question

A swimmer wishes to reach directly opposite bank of a river ,flowing with velocity 8m/s
can swim 10 m/s in still water. The width of the river is 480 m. Time taken by him to do so:
(a) 60 sec
(b) 48 sec
(c) 80 sec
(d) none of these​

Answer 1

Answer:

80 sec

Explanation:

swimmer can swim with velocity=10m/s

velocity of river =8m/s

total width =480m

$\sqrt{100 -64} =480/t\\\sqrt{36} =480/t\\t=80$