username: password: sign up Lost password?

Forums / Miscellaneous Discussions / Math Tricks/Problems

Math Tricks/Problems
22:39:40 Nov 16th 07 - Duke Borazon:

No, im saying ur equation is wrong

r^b(cos(a*pi)+isin(a*pi))^b = cos(a*b*pi)+isin(a*b*pi).  thats what it should be, but very nice anyways.

P.S. 200th post!


23:18:30 Nov 16th 07 - Ms. Gene Atalia:

I think you mistook me explaining to Sun with me solving your thing. I wasn't trying to solve your problem as such the thing in front wasn't necessary.


21:45:51 Nov 27th 07 - Lord Seloc:

whats, 1+2+3+4+5....etc....999+1000?


22:27:56 Nov 27th 07 - Lord Carnage:

an addition.
result: 500500

There's some formula to get that, but I forgot it ^^
So I did the lazy scripting way :P


22:40:02 Nov 27th 07 - Ms. Gene Atalia:

The formula is quite simple, it's n(n+1)/2, in our case n=1000 so we have 1000*(1000+1)/2 which is 500500.


08:18:12 Nov 28th 07 - Mr. Jenos:

That formula was said to have been invented by Gauss when he was just a child.


14:59:17 Nov 28th 07 - Mr. Sun:

seloc, use your head for your homework..

realign 1 to 100 backward, then add it back to the original sequence while paring the smallest to the largest. divide the sum by 2 cuz you added the sequence together twice, and u get the sum....

CHRIST!!!!! $%^$^%%&*^&*!^@#%$%@#&$%


15:09:49 Nov 28th 07 - Ms. Gene Atalia:

It's like 6th grade all over again isn't it Sun? :)


15:48:37 Nov 28th 07 - Lord Carnage:

ah right,
yeah i had figured that formula too when i was a child ^^
(1000/2)*1000+500... which is simplified to n(n+1)/2 XD


20:46:41 Nov 28th 07 - Lord Seloc:

Lol Sun I figured it out after I posted 0.o

anyway I thought it looked harder than it was : (, you post a problem.


21:03:38 Nov 28th 07 - Mr. Sun:

a real life related problem -

it suddenly started raining outside, and you dont have an umbrella with you. should you run fast to the building, or walk slowly to the building, in order to be the least wet in the process! what do you think is the main factor that will decide how fast you should go.

(this is something i just made up, and i have my own opinionated answer, someone could prove me wrong though)


21:21:48 Nov 28th 07 - Ms. Gene Atalia:

They tested this on mythbusters and their data showed that walking keeps you drier than running.


22:19:02 Nov 28th 07 - Mr. Sun:

o didnt watch that on mythbuster.

Assume the rain drop down in a perfect line towards you with a vertical speed (due to gravity and terminal velocity) of A and the horizontal wind is at the speed of B, and I walk at speed of C. Let's say each unit length of rain coming down is also 1 unit in weight for simplicity..... 

Then i take 1/C time to move 1 unit of distance....and you get rain from the top which is constant A, and also rain from the front or back which you run into with absolute value of |B-C|.

So (A+|B-C|) * 1/C give us the simple mass of rain onto you.
(A+B-C)/C=(A+B)/C-1 if B>C>0
Or (A-B+C)/C=(A-B)/C+1 if 0<B<C
Or (A+B+C)/C=(A+B)/C+1 if B<0 but C>0 (opposite direction)

(note that whatever you try to save by the horizontal speed difference always end up as a constant + or - 1)

Now lets assume B>C, so we are running towards the direction of the wind.
Differentiate this with respect to C, we have (A+B)*ln(C) which is always negative, so the original water mass function is a decreasing function.. meaning that C should be super big..... so running is better...? did I make some wrong assumptions or do some incorrect analysis? or over simplification of the problem?.... i am confusing myself now haha!


22:33:25 Nov 28th 07 - Lord Carnage:

to get the least west,
run sideways ^^


23:23:36 Nov 28th 07 - Lord Software Bug:

When they did a simple test on some program on Dutch television (Translated: National Science Quiz) they claimed that it made no difference if you ran or walked.


23:33:09 Nov 28th 07 - Lord Software Bug:

Apparently this is a question that has been bugging many people. Just search it on google and you will hit many sites:

According to
Discover magazine, Alessandro De Angelis, a physicist at the University of Udine, Italy, calculated some years ago that "a sprinter racing along at 22.4 miles an hour does get less wet, but only 10 percent less wet, than a hasty stroller (6.7 miles an hour)." Conclusion: running isn't worth the trouble.

However there are other sources that claim different: http://www.abc.net.au/science/k2/moments/gmis9749.htm says running is better with heavy rain fall and wind.

So if its heavy rain: Go run. If its just a few rain drops with no wind:  Not worth the hassle.



08:36:36 Nov 29th 07 - Lord Seloc:

or you could remember your umbrella next time.


11:20:45 Nov 29th 07 - Mr. Sun:

seloc wins the math thread!

p.s. we are too nerdy to remember umbrellas


14:44:14 Nov 29th 07 - Lord Carnage:

You're just too white and nerdy!
You wanna roll with the gangstas
But so far they all think You're too
White and nerdy...


22:25:17 Sep 20th 09 - VU Admin:

Probability problem

Two people are in love and are thinking of each other about 50% (half) of their time.
Now, what's the chance that they will think of each others at the same time?


22:26:18 Sep 20th 09 - Lord Stewie Griffin:

25%

1/4


22:37:58 Sep 20th 09 - Sir Pools Closed:

500%

10/2


22:39:45 Sep 20th 09 - Endless Death:

GA! 100%, they're in <3 ;)

or 0% cuz <3 is a lie .. like cake :D


18:32:44 Sep 21st 09 - Mr. Seloc:

Oh wow, this is like years old!
I'm much more intelligent now :P and could almost do some of these.

At a single moment in time, Possibilities:

X could be thinking of Y, Y could not be thinking of X.
X could be thinking of Y, Y could be thinking of X.
X could not be thinking of Y, Y could be thinking of X
X could not be thinking of Y, Y could not be thinking of X
Y could be thinking of X, X could not be thinking of Y.
Y could be thinking of X, X could be thinking of Y.
Y could not be thinking of X, X could not be thinking of Y.
Y could not be thinking of X, X could be thinking of Y.

2/8 or 1/4 or 25%.

 

Another probability question:
There are 50 people in a train, what are the chances two of them will have the same birthday?


18:39:19 Sep 21st 09 - Mr. Lanoc:

This is an interesting thread. Anyhow, in regards to that last one, it depends on whether it is one moment in time or how long, unless they're really slow thinkers. Since you didn't specify a time, they'll be bound to think of each other at some stage at the same time, unless one(or both) die very quickly. Besides that, the two events aren't completely independent, since when they're in the vicinity of each other they'll be more likely to think of each other than when apart. So it would be pretty much 100% - whatever the chance of any given person death is*2 at maybe ten minutes at most.


18:47:43 Sep 21st 09 - Mr. Lanoc:

Seloc, for that question, can there be more than two that have the same birthday?

(Edit, sorry. Birthday not problem...)


19:04:43 Sep 21st 09 - Mr. Lanoc:

Finding a calculator, sorry.

364/365 x 363/365 x 362/365 ... 315/365 is the chance of none of them being the same. This is 3%. So the chance that two have the same birthday is 97%.


19:17:34 Sep 21st 09 - Mr. Horus II:

For 2 w/same birthday:
13.425% if it is a 365 day year
13.338% if it is a leap year
13.416% if you take all years into account

For 3 w/same birthday:
1.765% if it is a 365 day year
1.756% if it is a leap year
1.763% if you take all years into account

For 4 w/same birthday:
0.227% if you take all years into account

I could be wrong, but thats my guess


19:18:35 Sep 21st 09 - Mr. Horus II:

Doh...


21:22:54 Sep 21st 09 - Mr. Seloc:

Mr. Lanoc


Report


17:47:43 Sep 21st 09

Seloc, for that question, can there be more than two that have the same birthday?

(Edit, sorry. Birthday not problem...)

ahh, yes.


21:36:26 Sep 21st 09 - Mr. Homo Ezatous:

If:


A = A life
B = Nerd
and C = Solving mathematic problems for fun

What is D?

B-A+C=D


21:39:24 Sep 21st 09 - Mr. Edd:

A life of solving mathematic problems for fun!


22:41:25 Sep 21st 09 - Mr. Horus II:

D = me!

Not as cool as someone who trolls and makes fun of people in an online war game


02:03:10 Sep 22nd 09 - VU Admin:

The answer to my question is that it's 50% chance that they will both think of each other at any given time.


02:25:24 Sep 22nd 09 - VU Admin:

To Mr. Homo Ezatous's question.

C = D-B+A, so if you solve math questions for fun:

+A =You have a life

-B = You are not a nerd.


02:35:32 Sep 22nd 09 - Sir Pools Closed:

Together, Bob and Joe have over 9000 dollars. Bob turned super saiyan. what % does Joe contribute to the total amount of money?


02:49:18 Sep 22nd 09 - Lord Stewie Griffin:

0.012345 %

DID YOU KNOW...

111,111 x 111,111 = 12 345 678 987 654 321


02:51:17 Sep 22nd 09 - Ms. Kittie Croft:



02:55:39 Sep 22nd 09 - Ms. Kittie Croft:


03:11:13 Sep 22nd 09 - Mr. Pingvinai Daug:


03:34:19 Sep 22nd 09 - Ms. Kittie Croft:


12:55:51 Sep 23rd 09 - Mr. The Beast:

hmm


13:07:30 Sep 23rd 09 - Mr. The Beast:

let me make one up.

Betty is a prostitute. who earnt money for her liveing..
Prostitutes make an avarage of 40 dollar/ hour.
with a standard deviation of 10 dollars.
she ows her Pimp 230 Dollars. bye the end of next week. ( she has 7 days)
if she doesnt pay up her pimp will destroy her.
what are the chanses betty will survive??


13:37:47 Sep 23rd 09 - Wolflord Karac:

pretty damn good, she only needs to work 6-8 hours to pay him off over the course of 7 days, the rest is her money.


16:29:14 Sep 23rd 09 - Mr. The Beast:

oops make that 40 dollars a days. she lives in asia..
then itl be 6-8 days that what i meant..


13:04:36 Sep 26th 09 - Sir Penguinus Prime:

lol asystole


[Top]  Pages:  (back) 1 2 3 4 5 

Login
Username: Don't have an account? Sign up!
Password: Forgot your password? Retrive it!

Forum bookmarks Reset views