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Probes

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Probes

by Aman verma » Tue Sep 27, 2011 5:25 am
Q: Robot Corporation US, manufactures robotic Probes and they test their robotic probes across various states. Once, early morning Probe A was sent from DC. to NY. Two hours later Probe B was sent from DC. to NY. However both the Probes reach NY simultaneously. If Probe A was sent from DC. and Probe B was sent from NY at the same time and travelled towards each other they would have meet in 1 Hour 20 Minutes. Find the time taken by Probe A to travel from DC. to NY.

a) 2h

b) 3h

c) 4h

d) 5h

e) 6h
Last edited by Aman verma on Tue Sep 27, 2011 7:49 am, edited 1 time in total.
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by user123321 » Tue Sep 27, 2011 5:56 am
P-----------Q
x

speed of A= x/t(say t is time taken for A to travel from P to Q)
speed of B= x/(t-2)

based on second clue..
(speed of A)*(1+1/3)+(speed of B)*(1+1/3) = x
substituting above speeds we get x variable cancelled on both sides and after solving a bit more we get...
1/t+1/(t-2) = 3/4

clearly x should be 4 for above equation to be true.

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by gmatclubmember » Tue Sep 27, 2011 6:05 am
let A take time t to reach NY then B take time (t-2) in hours.
distance b/w NY and DC 'd'.
Speed of A = d/t and speed of B = d/(t-2).

If they meet after 80/60 hours then in that time they both have covered distance d.
80/60*d/t +80/60 *d/(t-2) = d.
Solving we get t = 4 hours.

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by Aman verma » Tue Sep 27, 2011 7:56 am
OA[spoiler]c)[/spoiler]
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