For the more advance Math experts

[Biggamer3]

sounds simple, but its not

A Train usually goes 90 Miles per Hour

One day it only went 70 MPH

It got to its destination 4 minutes later than usual

How many miles did it travel?

 

[WCBias]

90 X x = Y
70 X x = Y+4

Is that right?

 

[steaktartar]

12

 

[steaktartar]

12x90 div by 60 is 18 12 x70 div by 60 is 14 so 12 miles

 

[levistep]

12

Going 90MPH gets you 12 miles in 8 minutes and it takes 10 minutes and change going 70mph.

The answer is 21 miles.

70mph = 1.16 miles/minute
90mph = 1.5 miles/minute

1.16mpm / 21 miles = 18 minutes
1.5mpm / 21 miles= 14 minutes

 

[wrongturn]

21 miles.

 

[goodcall]

21.027

 

[wrongturn]

distance = 90/60 * x = 70/60 * (x+4) = 21

 

[levistep]

Here is how you actually do the math out. Some of you guys probably did guess and check, but there is a legit way to figure it out. Just for your knowledge, this is Algebra 2 stuff, so it's like junior year high school math. It would be a difficult junior year high school problem though because most people have a hard time translating word problems into math equations.


Speed = Distance/Time

70mph/60mph = 1.16 miles per minute
90mph/60mph = 1.50 miles per minute

We substitute Y for distance and it remains constant in both equations. For time, we'll substitute X. The 70mph equation has X+4 because we know it takes 4 minutes longer.

1.16= Y/X+4
1.50= Y/X

You first have to put the second equation in y= form.
1.50=Y/X
Divide the both sides by X
1.5X=Y

Now substitute that back into the first equation
1.16= 1.5X/X+4

Solve that equation and you get X = 14

Plug back X=14 into our original equation and we get 14 miles for the second equation (90mph), and 18 miles for the first equation (70mph).

 

[steaktartar]

Going 90MPH gets you 12 miles in 8 minutes and it takes 10 minutes and change going 70mph.

The answer is 21 miles.

70mph = 1.16 miles/minute
90mph = 1.5 miles/minute

1.16mpm / 21 miles = 18 minutes
1.5mpm / 21 miles= 14 minutes

thanx i thought i got that answer too quick had to be wrong

 

[Biggamer3]

Going 90MPH gets you 12 miles in 8 minutes and it takes 10 minutes and change going 70mph.

The answer is 21 miles.

70mph = 1.16 miles/minute
90mph = 1.5 miles/minute

1.16mpm / 21 miles = 18 minutes
1.5mpm / 21 miles= 14 minutes

ope: :banger: :aktion033 :aktion033


Damn good job, i wanted to see how long it would take till someone gets the right answer.

I asked this question to a few college buddies of mine, and they were all stumped and were working on it for quite some time


Good job Levi!

 

[MIKEY.1TIME]

ope: :banger: :aktion033 :aktion033


Damn good job, i wanted to see how long it would take till someone gets the right answer.

I asked this question to a few college buddies of mine, and they were all stumped and were working on it for quite some time


Good job Levi!

great question and a special thanks for letting us know the answer, unlike other extraodinary people

 

[Illini]

Here is how you actually do the math out. Some of you guys probably did guess and check, but there is a legit way to figure it out. Just for your knowledge, this is Algebra 2 stuff, so it's like junior year high school math. It would be a difficult junior year high school problem though because most people have a hard time translating word problems into math equations.


Speed = Distance/Time

70mph/60mph = 1.16 miles per minute
90mph/60mph = 1.50 miles per minute

We substitute Y for distance and it remains constant in both equations. For time, we'll substitute X. The 70mph equation has X+4 because we know it takes 4 minutes longer.

1.16= Y/X+4
1.50= Y/X

You first have to put the second equation in y= form.
1.50=Y/X
Divide the both sides by X
1.5X=Y

Now substitute that back into the first equation
1.16= 1.5X/X+4

Solve that equation and you get X = 14

Plug back X=14 into our original equation and we get 14 miles for the second equation (90mph), and 18 miles for the first equation (70mph).

You say to just solve for x. But you said that you didn't guess. So how did you solve it? Is there an easier way than this?

7 =1.5x/x+4
6

7 (x+4)=1.5x
6

7x+28=1.5x
6

14x +56=x
18
18x=14x +56
4x=56
x=14

 

[Illini]

You say to just solve for x. But you said that you didn't guess. So how did you solve it? Is there an easier way than this?

7 =1.5x/x+4
6

7 (x+4)=1.5x
6

7x+28=1.5x
6

14x +56=x
18
18x=14x +56
4x=56
x=14

I guess I could have made it a little easier.
7/6=1.5x/x+4
7=9x/x+4
7x+28=9x
28=2x
x=14

Levi-how did you solve for x?

 

[Illini]

You could have also set it up this way.

Distance=rate(time)
y=1.5x
y=7/6(x+4)
7x+28=1.5x
6

7x+28=9x
28=2x
x=14

y=1.5(14)
y=21

 

[levistep]

You could have also set it up this way.

Distance=rate(time)
y=1.5x
y=7/6(x+4)
7x+28=1.5x
6

7x+28=9x
28=2x
x=14

y=1.5(14)
y=21

You just made it neater. I like working with decimals. Fractions don't support our troops. What I was talking about with the guessing is that you can keep guessing and checking different miles until you get the right one.