Math Problem

[Pains Requiem]

Y=2908x
100-x

Suppose a cost benefit model is given by the equation above, where Y is the cost in thousands of dollars of moving X% of pollutants. What % of pollutant can be removed for $40,000?

Homework where Im given a A,B,C,D answer but what I get doesn't match. Help please?


AREN'T YOU SUPPOSED TO:

Substitute 40 in for Y, and multiply both sides by 100-x to cancel out 100-x on bottom, and leave yourself with:
(100-x)40=2908X -> 4000-40x=2908x
4000-40x(+40x)=2908x(+40x)
4000=2948x

and then divide both sides by 2948 to get X?

 

[Emperor Pan I]

Y=2908x
100-x

Suppose a cost benefit model is given by the equation above, where Y is the cost in thousands of dollars of moving X% of pollutants. What % of pollutant can be removed for $40,000?

Homework where Im given a A,B,C,D answer but what I get doesn't match. Help please?


AREN'T YOU SUPPOSED TO:

Substitute 40 in for Y, and multiply both sides by 100-x to cancel out 100-x on bottom, and leave yourself with:
(100-x)40=2908X -> 4000-40x=2908x
4000-40x(+40x)=2908x(+40x)
4000=2948x

and then divide both sides by 2948 to get X?

if it is 40,000 why substitute in 40?

or am i missing something

 

[Pains Requiem]

Because Y is already in thousands.

It's a question on my girlfriends take-home math quiz and she's worked everything out like it is (even using 40,000) and still isnt getting a correct answer. Try working it yourself, reading the problem carefully. I'm not sure that X is all that your after in that problem. That shouldn't give you a % answer.

 

[Ninja_Blue]

Wait, is that supposed to be x MINUS 100, or x EQUALS 100?

 

[Emperor Pan I]

Wait, is that supposed to be x MINUS 100, or x EQUALS 100?

Y=2908x
....100-x

 

[ChrisH36]

If its solve by substitution. I believe you replace the Y with the bottom equation to work out X. Then fill in the answer for X to get Y.

 

[x42bn6]

This question is so stupid, I don't feel like answering it - no offence. But a note: Nobody has mentioned multiplying by 100 to get a percentage.*

 

[Jenny]

An Asian turning down the chance to do math? What has this stereotypical world come to!?

 

[Ntrik_]

Please don't tell me this is grade 11 or 12 math.

and yea this is a very stupid question, i did this in like grade 3 totdally lawl!

 

[Pains Requiem]

Me and her both have worked it out but her answer doesn't match any of the teacher's answers.

The answer we got was 1.36 something I believe, but thats not an answer.

Suppose a cost benefit model is given by the equation above, where Y is the cost in thousands of dollars of moving X% of pollutants. What % of pollutant can be removed for $40,000?

This is the part that I think is tricky. She worked out her problems the same way in school and got those answers right.

 

[Jenny]

You could just plug in the teachers answers to see if they check out.

 

[ChrisH36]

Me and her both have worked it out but her answer doesn't match any of the teacher's answers.

The answer we got was 1.36 something I believe, but thats not an answer.

Suppose a cost benefit model is given by the equation above, where Y is the cost in thousands of dollars of moving X% of pollutants. What % of pollutant can be removed for $40,000?

This is the part that I think is tricky. She worked out her problems the same way in school and got those answers right.

If that's the case.

Then you replace Y with 40k and then divide both ends of the equation by 2938.

Why that 100-x there is what I don't get.

 

[Pains Requiem]

Thjats 2908X DIVIDED by 100-x

The thing is, yeah she did that to get the answer but she wanted to know how to do it. She wanted to make sure she knew how to do it. Thats her college algebra class :/

 

[DigitalElite]

college algebra???

Shouldn't she be taking Calculus, pre-calac at the very least??

at the end I got .136 for x, if you multiply that by 100% you get 13.6%....is that what you want??

 

[Jenny]

college algebra???

Shouldn't she be taking Calculus, pre-calac at the very least??

at the end I got .136 for x, if you multiply that by 100% you get 13.6%....is that what you want??

Here it depends what you made on your ACT Math score and what degree you're going for. I had to take College Algebra. I think if you score high enough you don't have to take it.

 

[ChrisH36]

Thjats 2908X DIVIDED by 100-x

The thing is, yeah she did that to get the answer but she wanted to know how to do it. She wanted to make sure she knew how to do it. Thats her college algebra class :/

40000 = 2938x
40000/2938 = 2938x/2938

13.61470.... = x

13.61470 / 100 <--- not 100 - x...

13.61%

Don't you think that is a little too.... obvious?

 

[DigitalElite]

40000 = 2938x
40000/2938 = 2938x/2938

13.61470.... = x

13.61470 / 100 <--- not 100 - x...

13.61%

Don't you think that is a little too.... obvious?

Hell, I didn't even know college algebra was offered at my school until I looked it up, so anything is possible I guess?

 

[ChrisH36]

College Algebra was only designed for people that either sucked at math, forgot how it worked, or is a requirement for sciences.

 

[Malcom Sex]

You guys do realize that there is much harder algebra than this, right?

 

[ChrisH36]

Yeah, why do you think Calculus takes that position?