Tuesday, October 23, 2007

Any Math Lovers out there?

I am stumped on this problem:

The probability that a student owns a car is .66, and the probability that a student owns a computer is .72. If the probability that a student owns both is .48, what is the probability that a given student owns neither a car nor a computer?



BAH!
help me

19 comments:

Knitting Mama said...

Math was never my forte! I hope you find the answer!

Anonymous said...

Hey Suzi, Nance here. I emailed you my phone number. Call me. Hubby's an engineer ... former college math prof. He'll be in shortly and we'll get him on the line if you want.

Bunnies rock! They can't do math either, but they ARE cute. And if you dip their paws in tempera, they can paint...

Anonymous said...

Nance again. Google won't let me sign in. Baroo? But we sent you a lengthy e-mail explaining the prob.

Hope it helps!

Hugzes and stuff,

N

Renee said...

I wish I could help. I got a solid "B" in stats, but that was a couple years ago and my weakness was probability - never got the hang of that chapter. Happy Math-ing!

Nichoda said...

I was never able to handle a "riddle" hanging out there with no answer, so I need to know the answer to see how far off my guess was. LOL! Help!

Tarnok said...

Ack, Stats! I am more of a calc/algebra boy but I can try this one out for you. But I am liable to be wrong...

Alright, there are four distinct groups of people:

a) People who own ONLY a car
b) People who own ONLY a comp
c) People who own BOTH (.48)
d) People who own neither.

We are given (c) and partial information about (a) and (b) and we are asked to find (d)(how many has neither)

First we need to find (a) & (b) so lets isolate for people who ONLY have a car/comp.

SInce we know the "overlap" number is .48 lets subtract it from the rest.

Probability of people who only have a car = .66 - .48 = .18

Probability of people who only have a comp = .72 - .48 = .24

Now we know (a) = .18
(b) = .24
(c) = .48
(d) = ?
They must all add up to 1 (or 100%)
so now we do some algebra and plug in the values.

a + b + c + d = 1
.18 + .24 + .48 + d = 1
.9 + d = 1
d = .1

Therefore the people who own nether is .1 or 10%
------------

Ok please remember I might be WAYYYYYY off and I could just be making you suffer more. I am sorry if that is the case. I hope its not!

-PJ

Tarnok said...

Therefore the PROBABILITY**** of people who own neither is .1 or 10%.

(sorry about that mistake)

Seeking Simplicity said...

Okay... so where do the students live? And are they in college or high school? Male or Female? and how many people really know how a slide ruler works.

Good Luck...........

eM said...

very impressive. i think tarnok is an alien. math problems make my head hurt.

eM said...

i hope you get out of that class soon, cuz i think there is a good 'chance' that your brain may freeze or smoke itself

eM said...

hey ya'll, i want a cute, little, tiny person icon! who do i have to... i mean what do i have to do to create one?
oops, i realize that this comment was supposed to be in relation to your math problem, but i am pretty sure you have the answer, to your problem and mine hee hee.. so what is the probability that someone will help me create a little person icon? pleee-ase?

Nancyb said...

Oh ugh story problems...I sucked at math...still do...so wish I could help! Big hugs for ucky math problems! xo
NancyB

M said...

I just to let you know that I feel you pain!!!
Good Luck

bunwad@gmail.com said...

Ha, ha, ha, ha, he, he, ha, ah,a,ha, ha............................................

suzi blu said...

me too I dont have a kewl little picture icon how do we do it.
and
THANK YOU NANCYS FABULOUS MATH TEACHER HUSBAND and
THANK YOU TARNOK.


I am sorry to say that I will be a little pest to you both for the rest of the semester!

lynne h said...

suzi and em,

go into your google settings (or preferences, or whatever it's called)-- there's a place there for putting in a pic.

xxxooo

Jillian said...

Mathematically-challenged people of the world UNITE! :)

eM said...

BAM!

thanks tarnok, Aliens rok!

eM~

a simple offering said...

i love math. it seems to come easy for me but i have never taken a statistics class.