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These are college students. (Also weather doesn't work in such a simple way.)

Tags: facebook slaves

Brandon-
23 hrs . Montgomery, AL . Edited - It
MATH FRIENDS!!! I' m trying to do compound probability; to stretch my think
noodle. If something has a 50% chance of happening three different
occasions, whats the chance of it happening over all? I' m thinking the
correct answer is 75% 2 Assuming there is 50% chance of rain for 3 days in
row I did (50% % % = 150%, 150% % = 75% chance that its going
to rain at least once in this situation?) That' s just kinda bugging me that I
don' t remember this section of middle school math >. >
Like . : omment- Share
a Sean 1 Turn to fractions sir.
Ill 23 hrs . Like
Sean I Or Khan Academy it up
Ill 23 hrs . Like
Fga Sam t . 5% chance of it happening. Think of the probability of it not
tybalt happening at all. % it doesn' t happen at all which means
37. 5% it nap pens. This is assuming each turn is Independent of the others
Like. dbl

...

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Views:	10043
Favorited:	2
Submitted:	09/14/2014

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#5 - anon (09/14/2014) [-]

The rain was just an example you ******* , as stated in the information 50% chance of it happening and what are the odds of it not happening if you measure 3 instances.

50/50 25/25 /12.5/12.5 if you just divide it up, the only scenario where nothing happens in all 3 scenarios is if nothing happens in the 50% scenarios, so 1/2x1/2x1/2 is correct and the answer is 87,5%

Since when you say its a 50% chance you have already included all necessary information in your statement.

However a better scenario and more realistic would be a coin toss, 50/50, if you toss the coin x3 times its a 12.5% chance that all 3 tosses will land on head

#1 - kiaserzerg ONLINE (09/14/2014) [-]

so what if they are college students. their focus obviously isnt a phd in mathematics.

#4 to #1 - pizzapastasaurous (09/14/2014) [-]

...You hope.

#14 to #1 - joekerr (09/15/2014) [-]

Yeah, because high school grads are not qualified enough.
/irony

#17 to #14 - kiaserzerg ONLINE (09/15/2014) [-]

you would be surprised how much completely useless **** is forgotten, and how easily.

#18 to #17 - joekerr (09/15/2014) [-]

??? surprised? well, define useless. i know a lot who don't know **** anymore (and actually never did), but that's not my issue here. this is simple statistics. almost every major includes them (this is also where for example most psychologists fail at) and shouldn't be such a big deal.
someone with a phd in math has seen some real serious unnecessary **** already at his bachelor's ... ;)

i just realized i took an exaggeration literally. weeelll. not native-english speaking, sry about that.

#19 to #18 - kiaserzerg ONLINE (09/15/2014) [-]

its cool, like most americans, my native is english, and i can barely speak it sometimes.

#20 to #19 - joekerr (09/15/2014) [-]

well, wasn't really a language issue. just overreacted to something i found narrow-minded.

#9 - chrisel (09/14/2014) [-]

12,5%

#11 to #9 - anon (09/15/2014) [-]

12.5%, you damn eurofag

#21 to #11 - chrisel (09/15/2014) [-]

Americunt.

#13 - krazeed (09/15/2014) [-]

I dont wanna post my thought process on this because I feel like stubborn/stupid people might get mad at me and flame me, but my inner mathlete is screaming at me... sigh...

The guy who posted (Sam) should be right. He explained it somewhat poorly, but he is correct. The question which Brandon asked was what are the chances that it would rain at least once in this situation. So we think of it this way: Theres a 50% chance for rain to occur each day, which also means that there is a 50% chance that the rain will not occur each day. We take 50%, which is 1/2 in fraction form, and multiply it by itself 3 times (i.e. 1/2 * 1/2 * 1/2) which would equal 1/8th, or 12.5%

Now, this is where people usually get confused. The probability 1/8th is not the likelihood of rain in general; rather, it is the chance of rain occuring EITHER all 3 days, or none of the 3 days. Lets assume that in this case it means none of the 3 days. Remember the initial question was: what is the chance of rain on at least one day? So, we take the probability of it not happening at all (12.5%) and subtract it from the value which encompasses every outcome (100%). 100-12.5 = 87.5, therefore the correct answer to this brainteaser would be 87.5%

The biggest issue Im seeing with people who argue about math "puzzles" (i guess) like these ones are that they dont read the problem clearly. I mean, thats one of the biggest things they teach you in elementary and middle school: read the problem carefully. At least that was the case with my education. Its upsetting that people who dont pay attention think they are right when they dont even know what theyre talking about. (And before I get flamed for that one, Ive done it before in the past too, and Im not perfect. I work immensely hard to either understand something, or not be overzealous about it, in order to uphold that moral)

Anyways, I hope that this was worth the read to someone... Later.

#15 to #13 - joekerr (09/15/2014) [-]

There's also a wording issue. The propability for it to happen at least once is 87.5 % (P[#rainy days higher 0]). However, if you look at it to happen only once (P[#rainy days = 1]), you have another solution. As it is a binomial experiment, you get 3 * (1/2)^3, which is 37,5 (same two times, and everyday is the same as not at all, 1/8 ... 3/8 + 3/8 + 1/8 = 87,5 %; imho that complement-set-solution is way better than the "numerical").

#16 to #13 - joekerr (09/15/2014) [-]

Sorry, overread, he did say at least.

#7 - anon (09/14/2014) [-]

isn't it 79.37% chance because if x is the probability of it happening once then its got to be x*x*x=.5 or x^3=.5 so it would be x=.793701 like think about if you wanted to calculate the probability of a coin landing heads up 3 times in a row. original probability is 50% and probability of it happening 3 times is 12.5% or .5^3

#8 to #7 - anon (09/14/2014) [-]

misunderstood the problem, disregard my stupidity

#12 - anon (09/15/2014) [-]

It clearly a low chance of rain on one of the three days. If we take the fact that a meteorologist can't predict the weather, divide that with the amount of times he/she has actually been right then take into account the fact that people are stupid and disregard the clouds or swell when they fall off a boat and drown during a terrible storm then we can extrapolate that probability doesn't matter because natural selection will help chance out once in a while

#3 - anon (09/14/2014) [-]

They don't know how combine statistical information. I'm sure you don't know something related to their major. and imo math isn't a test of intelligence, only how well you memorize the directions Engineering- CS major here

#6 to #3 - robuntu (09/14/2014) [-]

This isn't something Math majors need to know - this is something high school freshman should know. Basic statistics/probability is pretty important for people to know. It's like saying college students shouldn't know 'there vs. their' unless they are English majors.