help me with a math problem

X/(X+Y)

Z = X/X + Y/Y - XY/XY.
Roomate's share = (Total Rent) - Z

If it is a him, a better formula would be: subtract your income from his, if the difference is greater than the rent, then he should pay it all.

The original equation asks you to figure out what percentage of total household income you bring in: X/(X+Y) = your income divided by total you-and-him income. So if you make like 47% of total money, then you pay 47% of rent, or whatever else.

The way I put it is actually maybe more complicated -- figuring out what percent of his income you make, then arranging to pay that percent of what he pays for everything.

You're better off doing it the first way, so you can go around saying "listen, bub, I bring home 46.8% of the bacon in this house, and I say we're renting Tuck Everlasting."

I have two loans, one for 15000 at 5% over 3 years, and one for 40000 at 10% over 30 years. If I have money to pay more than my minimum payment, is it better to put it toward the second one because the interest rate is higher (and I would be eating away at the principal early in the life of the loan), or is it better to put it toward the first one because the minimum payment is higher, so once I get that one paid off, it frees up a good chunk of my budget?

I hope that made sense.

Let X = his adjusted rent share
X + .78X = RENT
1.78x = RENT
x = RENT/1.78

But I like the first one better, since it gives her a number that expresses her share of total income (and not just her earnings relative to his).

but it all falls out really easy. dividing by 1+salary ratio makes sense because then youre dividing by the number of "large shares" being paid, which is 1.75 instead of 2, in the equal rent case.

40000*(1+(.1/12))^12 >>>>> 15000*(1+(.05/12))^12

so anything you can do to keep that fast interest from piling up is much better.

Putting $100/month toward the lower interest loan saves ~$225 and shortens the term by .5 years.

To put actual numbers to it. The magic of compound interest.

This is a question about using the Simplex method to solve linear programming problems (uhh.....caek?)

- - for anyone who could help but doesn't want to read the rest of this, just skip to the last paragraph, where I finally get around to asking my question - -

I skipped class all week in one of my courses, because we're going over linear programming and I arrogantly figured I'd know everything he was going to teach because I did a bunch of linear programming a few semesters ago. But I had never solved problems using the simplex method, which is apparently what he was teaching. Now I have a homework problem that I'm required to solve using simplex, and I have to show my beginning and final tableaux.

I spent a few hours reading tutorials and doing practice problems, and I understand the basics of it. Then I found this online tool that basically does the leg work for you. You put in the objective function and the constraints, and then it solves it for you, and lays out the steps it took to get there.

Tableau #1
b      m      cl     pl     s1     s2     s3     s4     p             
1      1      1      1      1      0      0      0      0      650000 
0      0      0      1      0      1      0      0      0      162500 
1      0      0      -1     0      0      -1     0      0      1      
0      1      0      -1     0      0      0      -1     0      1      
-0.06  -0.07  -0.075 -0.095 0      0      0      0      1      0      
Tableau #2
b      m      cl     pl     s1     s2     s3     s4     p             
0      1      1      2      1      0      1      0      0      649999 
0      0      0      1      0      1      0      0      0      162500 
1      0      0      -1     0      0      -1     0      0      1      
0      1      0      -1     0      0      0      -1     0      1      
0      -0.07  -0.075 -0.155 0      0      -0.06  0      1      0.06   
Tableau #3
b      m      cl     pl     s1     s2     s3     s4     p             
0      0      1      3      1      0      1      1      0      649998 
0      0      0      1      0      1      0      0      0      162500 
1      0      0      -1     0      0      -1     0      0      1      
0      1      0      -1     0      0      0      -1     0      1      
0      0      -0.075 -0.225 0      0      -0.06  -0.07  1      0.13   
Tableau #4
b       m       cl      pl      s1      s2      s3      s4      p               
0       0       1       0       1       -3      1       1       0       162498  
0       0       0       1       0       1       0       0       0       162500  
1       0       0       0       0       1       -1      0       0       162501  
0       1       0       0       0       1       0       -1      0       162501  
0       0       -0.075  0       0       0.225   -0.06   -0.07   1       36562.6 
Tableau #5
b      m      cl     pl     s1     s2     s3     s4     p             
0      0      1      0      1      -3     1      1      0      162498 
0      0      0      1      0      1      0      0      0      162500 
1      0      0      0      0      1      -1     0      0      162501 
0      1      0      0      0      1      0      -1     0      162501 
0      0      0      0      0.075  0      0.015  0.005  1      48750  

I follow the logic of each progression EXCEPT for the last one. How does the last row get adjusted like that without affecting the others?

Oh, nevermind, I've got it. For row5, it should be .075row1 + row5. I'm not sure why that seemed so wrong 5 minutes ago.

Disregard (shouldn't be too hard)

the only thing i know about math... is that you go on thundays!!!!!!!!!!!!!!!!!

Help!

I have been asked to calculate the percentage difference between the amount of time people spent on a website in week 1 (6 minutes 3 seconds) and week 2 (5 minutes 11 seconds).

I can't figure out how to figure it out. I am not smart. Thank you.

Or would it work if I converted everything to seconds, then did 363 - 311, divide that number by 311, then x it by 100?

That seems wrong.

363 is 100%
1% is 3.63
311 divided by 3.63 is 85.67

People spent 14% less time the second week.

Or, what you said, but you divide by 363 and then x 100.

Now calculate the difference between week 2 and 3 if the third week would be 363 again! (Hint: it's not 14%) :-)

Hmm... People would have spent 16.7% more time the third week?
(as in, 311 - 363, divided by 311, then x 100?)

Thank you for the help, by the way!

Yes, that's it! ( No problem :-) )

(for k = 0 to ∞) Why does 1 = ∑(.2^k)*Po = Po/(1-.2) ?

I dont understand how to get the last part: Po/(1-.2)
Po = P_0 or P subscript 0

hah nvm!, someone on yahoo answers actually did it for me:

For an infinite geometric series with common ratio r satifying |r| < 1, the sum is known.

∞
Σ a r^k = a/(1-r)
k = 0

This is the result used to get that last line.

∞
Σ Po (0.2)^k = Po/(1-0.2) = 5Po/4.
k = 0

If this sum is supposed to equal 1, then Po = 4/5.

Who are these people on Yahoo answers that do everyone's homework? Every time I googled something for o-chem back in the day, someone would have always posted the question direct from my o-chem book to Yahoo answers, and it would always have at least one thoughtful, accurate answer. Who answers strangers' o-chem problems for fun????

do they get paid? I remember the google answers dudes would get paid. or there would be a bounty.

or maybe the helpful dudes treat it as a study tool, i.e. explaining it shores up their own understanding of the problem

As far as I know, I mean the question-asker was always just throwing the question up, no offer of anything in return. SO I don't think answerers were getting paid. It was weird!

It was really helpful to me, though. I don't think I could have got through o-chem w/out the internet.

That's what All Experts is all about! You get $0. I suppose there's really no other reason that people wanting to help other people.

CaptainLorax, I know you're question has been answered, but just out of curiosity what's P_0? Just a constant?

yes

what is integer n where 90% of n = 6?

http://www.theargus.co.uk/news/quirkies/8453119.Bognor_dog_swallows_couple_s_pension_cash/

That doesn't work the way you think it does.

Six twenty pound notes = £120.

Since they had at least 90% of the actual paper body of the six notes, they were able to exchange the pieces for new notes.

what is the law in the uk regarding damaged notes?

It would be funny, though, if you only got a percentage value of torn paper money.

"The corner is torn off this note, therefore it is only worth 90p"

Yeah that did occur to me. "He was able to piece together 90% of the notes" would have made things clearer.

I envision this couple as being smack addicts.

Get 10 x £20 notes. Cut 10% off each of them. Stick all the bits together. Now you've got £220.

!

Of course you'd need some sort of backstory like your dog had chewed it all up or something.

thank god it's not a meth problem

Hi. I have a math problem.

I'm dealing with a Facebook Page with 14058 fans. Over the month of April, the page has grown 1.22%.
1. If the page continues to grow at its current rate, how many fans will it have by the end of Dec?
2. Also, what % growth each month would be needed in order to reach 50 000 fans by the end of Dec?
3. Is there a formula I can use to calculate this stuff?

Argh math makes me feel really stupid please help!!

it depends on whether that growth is continuous or monthly

if that's a monthly growth rate, you just need to multiply the number of fans by 1.0122 to get the next month. I'd do it in a spreadsheet for multiple months so you can just repeat the multiplication but using the previous month's figures.

1. 14058 * (1.0122^8)
2. 14058 * x^8 = 50000

it seems to be monthly from the q tbh?

8 months of 1.22% increase = 1.0122^8 = about 10%, 15490 fans.

50000 / 14058 = 3.556

8th root of 3.556 = 1.17118 - 17% increase every month.

I think what iatee's asking is, you've gained 2535 fans in April, which is also 1.22% of your previous total - are you more likely to keep gaining 2535 per month or 1.22% per month?

So it's basically like the formula for compound interest? I did try that initially but my final number looked way off so I thought it was wrong! Turns out I just can't add...
I don't know the dif bwn monthly and continuous sorry, if it helps I have to do this report each month so maybe monthly is the interval to aim for.
Thanks for the responses.

xpost I would say 1.22% pm
(funnily enough the growth rate was 20.56% throughout march so this isn't going to be an exact science)

http://www.slate.com/articles/health_and_science/science/2013/03/facebook_math_problem_why_pemdas_doesn_t_always_give_a_clear_answer.html

At first, I thought 1 was the obvious and only answer (we call it BEDMAS, not PEMDAS), but now I see the case for 9. "Implied multiplication by juxtaposition"--I like the sound of that.

it's 9 the way i was taught. feel like really this is a notation issue, not a rules issue.

^^^^^otm

re: notation issue

lol at this

CAD OTM

lol @ u guys emphatically otm'ing some arithmetic

^^^^^otm

― brimstead, Wednesday, March 13, 2013 5:46 PM (16 minutes ago) Bookmark Flag Post Permalink

re: notation issue

― brimstead, Wednesday, March 13, 2013 5:46 PM (16 minutes ago) Bookmark Flag Post Permalink

nerds!!

here's a good one

20/5 = 4, obviously

but does that represent ... five groups of four, or four groups of five?

IMO that represents 5 groups of 4

in other words, when we divide 20 by 5 are we seeing how many groups of five fit into the 20, or are we seeing how big the parts are when we divide 20 into five equal parts

I read it as 2 times 0 divided by 5

well you're just hopeless

again, it's ambiguous

CAD OTM

― Darth Icky (DJP), Wednesday, March 13, 2013 1:48 PM (1 hour ago) Bookmark Flag Post Permalink

mark this as the time a cs dude otm'd an english major re: a math problem

as the first asian to post itt I do not otm cad, thereby banishing him into the lost lands where he will be forced to wander forever

back to my rightful place

I think that where one way of notating something has a greater possibility for ambiguity than the other, the less ambiguous way should be preferred. In the above example, if you wanted to make clear that you were looking for the answer 9, you would notate it as (6 / 2)(1 + 2) (assume the / is the other division symbol, the slash has its own problems). So when I see it without the first set of parentheses, I assume the result is supposed to be "1" and not "9".

who uses an obelus anyways

yeah that's my #1 issue with this thing

Hurting otm

j. otm

if you typed this into a calculator, you would get 9. 9 is the answer.

Thank god none of this has real life implications.

calculators are invariably fucking shit tbh

what does that even mean

you have to fuck about with brackets on most calculators to perform tasks that don't require brackets when written down

bidmas/bodmas being a better system than the inadequacies of calculator design imo

i don't really get why you would, like, assume the answer and work backwards based on the notation or whatever hurting is saying above

I'm not assuming the answer, I'm assuming that the person who wrote the problem would want to write it in the clearest way possible so that I get the answer.

that is the worst possible assumption one can make about a math problem, particularly one that is intended to make people on Facebook fight

this math problem really makes u learn a lot about urself

well, no, in general what hurting said is true. a lot of the times a word or symbol will have more than one definition & it's up to the reader to understand which, based on the context

(xp)

tbf, the article uses almost identical logic to mine to come to the opposite conclusion, so maybe it's just the way I was taught

Left to Right

i've got a math/logic problem for you guys

ok so there's an island with 100 green-eyed natives and 900 black-eyed natives. all natives adhere to a religion where if u ever know your own eye-colour, you have to commit ritual suicide. one day, an explorer shores up on the island and says "at least one person on this island has green eyes." by the end of the following day, every green-eyed person has killed themselves. why?

imperialism

Left to Right

― brimstead, Wednesday, March 13, 2013 6:28 PM (29 minutes ago) Bookmark Flag Post Permalink

yeah this

hey flopson is it because they looked at everyone on the island and counted 99 people with green eyes, whereas if you had black eyes you counted 100?

https://xkcd.com/solution.html

that ... does not seem to be the same problem

i just realized the problem with what i said is that if they knew how many had green eyes they could have figured it out before explorer showed up to announce one person on this island has green eyes

ok so if there's only one green-eyed person it would be immediate suicide, because they realize it's them ... if there's two green-eyed persons, the first sees the second and thinks: why haven't they committed suicide yet? oh, because there must be another green-eyed person. gadzooks! it's me!

and from there it's proof by induction.