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?

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.