Question

A boat takes 9 hrs to travel from A to B upstream. If the river current is 3 km/hr, how long will it take to travel downstream between B and A ?

Answer 1

I think we need to know the A to B distanceLet's assume the distance from A to B = 180 miLet s = boat speed in still waterthen(s-3) = effective speed upstream (A to B)Find s9(s - 3) = 180
 simplify, divide by 9s - 3 = 20s = 20 + 3s = 23 mph speed in still water:(s+3) = effective speed downstream (B to A)Let t = time required to go downstreamt(23 + 3 ) = 18026t = 180t = 180/26t = 6.923 hrs to go downstream (B to A)

Answer 2

let us assuume the distance to be 100m

we get 100 = 9(x-3)
x = 100/9 + 3
substituting in 100 = y(x+3)
we get y = 900/154 = 450/77...
it will tke around 5.8 hours


thanks for reading