Answers

2014-05-22T11:06:28+05:30
let the speed in still water be x km/hr.
upstream the speed will be x-1.5
distance = 2km
time taken upstream = 2/(x-1.5)
..
downstream speed = x+1.5

distance = 2km
time taken = 2/(x+1.5)
..
he takes thrice the time upstream. 
2/(x-1.5) = 3*(2/x+1.5)
(x+1.5)(x-1.5)=3
x^2-2.25=3
x^2= 0.75
=0.87 km/hr
0
Let the speed in still water be x km/hr
then upstream speed is (x-1.5)
total distance +2 km.
time taken upstream = 2/(x-1.5)
downstream speed = x+1.5

distance = 2km
time taken = 2/(x+1.5)
..
he takes thrice the time upstream.
2/(x-1.5) = 3*(2/x+1.5)
(x+1.5)(x-1.5)=3
x^2-2.25=3
x^2= 0.75
=0.87 km/hr