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by logitech » Wed Jan 07, 2009 1:44 am
so the distance is (20-4)x5 = 16x5 ( there is no need to convert min to hr)

16x5=4xt

t=20 min
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by vivek.kapoor83 » Wed Jan 07, 2009 1:55 am
relative speed -16 mph
Distance covered in 5 min - 1.3 miles
Now, at 4mph it will take -19.5 min to cover 1.3 mile...where i am gng wrong.pls correctme
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by piyush_nitt » Wed Jan 07, 2009 2:10 am
vivek.kapoor83 wrote:relative speed -16 mph
Distance covered in 5 min - 1.3 miles
Now, at 4mph it will take -19.5 min to cover 1.3 mile...where i am gng wrong.pls correctme

Bold part equals to 1.333333333333333

thats the reason that your answer needs additional 30 seconds.
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by logitech » Wed Jan 07, 2009 2:11 am
vivek.kapoor83 wrote:relative speed -16 mph
Distance covered in 5 min - 1.3 miles
Now, at 4mph it will take -19.5 min to cover 1.3 mile...where i am gng wrong.pls correctme
Vivek this why you should not convery some X to Y ( miles/hr to miles/min) and convert it back!

Here is why you get 19.5:

16 miles 60 min

X miles 5 minutes

X = 16x5/60

X= 4/3

4/3 is 1.3333333333333333333333333333333333333 NOT 1.3

So if you use 4/3 instead of 1.3

4/3 = 4mph x TIME

TIME = 1/3 hr

1/3 hr is 20 minutes.
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by vivek.kapoor83 » Wed Jan 07, 2009 2:43 am
hmmmm....strange...small mistake.......and wrong result............Thanks ligtech
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