# A boat takes 9 hrs to travel from A to B upstream.If the river current is 3kmph.How long will it take to travel down stream between B & A?

1
by jagjitKhurana76

• Brainly User
2015-05-25T09:41:11+05:30
Let Velocity  of boat =  x km/hr
River Current = 3km/hr
Net upstream speed=  (x - 3 ) km/hr
Net Downstream speed  = (x+3 ) km/hr
Upstream time = 9 hrs
Let distance between A and B = d km

we know that ,
speed = distance / time
Upstream :
x - 3  =  d / 9
or 9(x -3) = d ...................... 1st
for Understanding Purpose Only:
(
9 = d/x-3
by Hit and Trial , we can have
d= 27 km and x=6km/hr )
DownStream  :
Let the boat takes time = T to travel between A and B .
x+3 = d / T
T(x+3) = d  -------------- 2nd
from 1st and 2nd , we get
T(x+3) = 9 (x-3)
or T = 9(x-3)/x+3
for Understanding Purpose Only:
(if U use Hit and Trial of Equation 1st you can have T = 3 hours)

Here we can have T in terms of x , because distance between A and B is not given .

So we can have value of T in terms of x or d only.

Hope this helps you!!

Thank You!!