Need help with finding distance. Please.

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megaxero

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Sep 16, 2008
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So here's the problem:
A subway travels 60mph from Glendale to Midtown. Another traveling at 45 mph takes 11 minutes longer for the same trip. How far apart are Glendale and Midtown?

I'm having trouble finding the right distance I keep doing it over and over again but i can't seem to get it right. Please help.
Thanks in advance for anyone willing to help.
 
megaxero said:
So here's the problem:
A subway travels 60mph from Glendale to Midtown. Another traveling at 45 mph takes 11 minutes longer for the same trip. How far apart are Glendale and Midtown?

I'm having trouble finding the right distance I keep doing it over and over again but i can't seem to get it right. Please help.
Thanks in advance for anyone willing to help.
Click to expand...

Please show your work/thoughts - so that we know where to begin to help.

How do you know you are not getting it right - book's answer can be wrong.
 
Well I did this but now I think I got it right but I don't know.

60=d/t
t=d/60

Then I got that and I plugged it in here:

45=d/(t +11) the 11 is from the 11 minuted longer it took
45(t + 11) = d
45(d/60 +11)=d
.75d + 495 = d
495 = .25d
1980 miles = d

That's what I did right now but I'm not sure if its right.
 
megaxero said:
So here's the problem:
A subway travels 60mph from Glendale to Midtown. Another traveling at 45 mph takes 11 minutes longer for the same trip. How far apart are Glendale and Midtown?

Thanks in advance for anyone willing to help.
Click to expand...

First rule in doing word problems is to NAME THINGS. What are you asked to find? Looks like you are asked to find the distance between Glendale and Midtown. So,

let d = distance between Glendale and Midtown in miles

Would you agree that both trains travel the same distance?

A basic relationship that you MUST know for this type of problem is that

distance = rate * time
or,
distance / rate = time

We know that the time for the second train is 11 minutes (or 11/60 hour) more than the time for the first train.

time for second train = time for first train + (11/60)

The first train travels that distance d at a rate of 60 mph. The time for the first train is distance / rate, or d/60.

The second train travels that distance d at a rate of 45 mph. The time for the second train is d/45.

time for second train = time for first train + (11/60) hours

Substitute the expressions we've found for the time of the first and second trains:

d/45 = (d/60) + (11/60)

Solve that for d, and you will have the distance between the two cities.
 
f = faster speed [60]
s = slower speed [45]
e = extra time by slower (11/60)

distance = fse / (f - s) : foreverafter known as the "Denis Distance Formula" :roll:

60(45)(11/60) / (60 - 45)
= 495 / 15
= 33
 
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