Two boats are heading towards each other

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Two boats are heading towards each other

by GMIHIR » Tue May 01, 2012 8:58 pm
Two boats are heading towards each other at constant speeds of 5 miles/hr and 20 miles/hr respectively.
They begin at a distance 20 miles from each other. How far are they (in miles) one minute before they collide ?
A 1/12

B 5/12

C 1/6

D 1/3

E 1/5
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by niketdoshi123 » Tue May 01, 2012 9:49 pm
Relative speed = 25miles/hr
= 25/60
= 1/12 miles/min

Hence the answer is A

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by sam2304 » Tue May 01, 2012 9:55 pm
niketdoshi123 wrote:Relative speed = 25miles/hr
= 25/60
= 1/12 miles/min

Hence the answer is A
It should be B right ? ?
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by niketdoshi123 » Tue May 01, 2012 10:58 pm
The question asks: how far are they 1 minute before they collide, so we need to find how much distance they traveled in 1 minute.
As their relative speed is 1/12 miles/minute
distance = 1/12*1= 1/12miles

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by sam2304 » Wed May 02, 2012 1:49 am
niketdoshi123 wrote:The question asks: how far are they 1 minute before they collide, so we need to find how much distance they traveled in 1 minute.
As their relative speed is 1/12 miles/minute
distance = 1/12*1= 1/12miles
There is a mistake in your calculation. I tried to point that out.

25/60 = 5/12 and not 1/12.
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by niketdoshi123 » Thu May 03, 2012 2:02 am
my mistake