Upstream:
r = v-3
t = t+0.5
d = 90
Downstream:
r = v+3
t = t
d = 90
rt = d
RT(upstream) = RT(downstream) ; that is, 90 = 90
(v-3)(t+0.5) = (v+3)t
eventually, I got to 2t^2 + t - 15 = 0, so t = -3 or 2.5
The answer cannot be negative, so I chose 2.5
GMAT Prep Test 1 PS 2
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neeraj_99
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instead of using algebra, better to backsolve
speed downstream is 6m/hr more than upstream speed, distance is same
A: t=2.5 hr, D=90, hence s=90/2.5=36m/hr
hence speed upstream=36-6=30 m/hr, hence t=90/30=3 hr,which satisfies the condition in the question
speed downstream is 6m/hr more than upstream speed, distance is same
A: t=2.5 hr, D=90, hence s=90/2.5=36m/hr
hence speed upstream=36-6=30 m/hr, hence t=90/30=3 hr,which satisfies the condition in the question
Hi friends ! Just started GMAT prep. Hope to share thoughts, experience, joy and agony of GMAT prep journey.
Regards; neeraj
Regards; neeraj
