Speed = distance/time
use this and set up the 2 equations
For going up the river :
90 = t * (v - 3)
For going down the river :
90 = (t - 0.5) * (v + 3)
solve for the equations.to get 2.5
hence 2.5 for downstream and 3 hrs for upstream..
hope it helps..
PS: be careful while solving the equation...
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Source: Beat The GMAT — Problem Solving |
D=RT
Time taken upstream = 90/v-3...(1)
time taken downstream= 90 / v+3..(2)
upstream takes 0.5 hour more..
thus..( 90/v-3) - (90/v+3) = 0.5
solving we get v = 33
substitute in (2)...
time taken = 90/36= 2.5
Time taken upstream = 90/v-3...(1)
time taken downstream= 90 / v+3..(2)
upstream takes 0.5 hour more..
thus..( 90/v-3) - (90/v+3) = 0.5
solving we get v = 33
substitute in (2)...
time taken = 90/36= 2.5
Can any of you please provide how you solved the equation? It's taking me forever to solve for either v or t. any suggestions?
never mind - figured it out. that was a longggggg process though...don't know if i can do that in two minutes..more like 4-5 minutes!kshin78 wrote:Can any of you please provide how you solved the equation? It's taking me forever to solve for either v or t. any suggestions?
