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Time/Travel Problem==PLEASE HELP!!

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Time/Travel Problem==PLEASE HELP!!

by Rod10159 » Wed Oct 13, 2010 3:48 pm
Hi!
Hoping someone can give me a clearer explanation than the book on the following problem:

-- How many miles does it take to travel 120 miles at 400 miles per hour?
a. 3
b. 3 1/3
c. 8 2/3
d. 12
e. 18

I keep trying to "work it" but keep getting stuck.

PLEASE HELP!
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by limestone » Wed Oct 13, 2010 4:52 pm
I think there is a typo here. How many minutes not miles.

The fomulas:

Time = distance / speed

The distance here is 120 miles
Speed: 400 mph
So the time is : 120/400 = 3/10 hour
The time in minutes = 3/10*60 = 18 minutes

So pick E.
"There is nothing either good or bad - but thinking makes it so" - Shakespeare.
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by neerajkumar1_1 » Wed Oct 13, 2010 6:13 pm
limestone wrote:I think there is a typo here. How many minutes not miles.

The fomulas:

Time = distance / speed

The distance here is 120 miles
Speed: 400 mph
So the time is : 120/400 = 3/10 hour
The time in minutes = 3/10*60 = 18 minutes

So pick E.
couldnt agree more with limestone...
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by fskilnik@GMATH » Thu Oct 14, 2010 4:39 am
How many minutes does it take to travel 120 miles at 400 miles per hour?
a. 3
b. 3 1/3
c. 8 2/3
d. 12
e. 18
Alternative method (I like to call it "Units Control", but it is just Physics dimensional analysis...)

1 h
------------ x 120 miles = 3/10 h.
400 miles

60min
------------x 3/10 h = 18min
1 h

I do all that in just one line, but here I could not type the way I´d like to show you in a clear way...

The idea would be "(h/mile) x mile x (min/h) = min" and the numbers associated with the units... I hope you "got the picture".

Regards,
Fábio.
Fabio Skilnik :: GMATH method creator ( Math for the GMAT)
English-speakers :: https://www.gmath.net
Portuguese-speakers :: https://www.gmath.com.br
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