Question

Five pairs of socks (colored by pair white, black, blue, red and green) are mixed up in a drawer. Socks are pulled out one at a time. What is the probability that you will need to pick out exactly four socks to get the pair of white socks?

Answer 1

Do u have answer key with u?

Answer 2

yes

Answer 3

i usually know the answer to most of my questions...

Answer 4

So..wat shuld be the answer?

Answer 5

why?

Answer 6

To..Check..wheather i got it Correct or not....

Answer 7

i would like to avoid random solutions as much as possible so giving the answer is a no can do

Answer 8

Hm...hm...just to check... Combination has a role to play here

Answer 9

so that means you're not sure?

Answer 10

The fourth sock drawn must be white, and it must be the 2nd white sock, so it's the chance of drawing that one remaining white sock from the (5 pairs - 3 previous socks) = 7 remaining socks in the drawer.

But that's just for the last sock drawn...

Answer 11

that sounds a bit.....short

Answer 12

well, you also have to find the chance of drawing exactly one white sock from your first 3 picks.

Answer 13

It sounds to me like "pick exactly one white sock from the first three selections, then draw the remaining sock on the fourth selection"

Answer 14

that would be combination yes?

Answer 15

I am thinking "yes" for the first 3...

Answer 16

Yes... There are 10 Socks choosing 4 @ a time...

Answer 17

order doesn't matter... white sock on draw 1 is equivalent to white sock on draw 3. But the fourth draw must be white.

Answer 18

i assume 3C1 for the first white sock

Answer 19

no, @yahoo! it's pulling one at a time, not "choose 4 from 10"

Answer 20

so it would be 3C1 * 8/10 * 7/9 * 2/8 * 1/7

yes?

Answer 21

I am bad with notation...

can you talk it through? i.e. translate that last statement? :)

Answer 22

one seventh?

Answer 23

no, I got that part... It's just taking me a minute to recall the 3C1 notation

Answer 24

it's just 3

Answer 25

fancy way of writing 3

Answer 26

why did you start then with 8/10 ? I can see the "without replacement" in the declining denominators...

sorry, the concept seems clear to me, but I'm rusty on actually setting up the math.

Answer 27

well....because there are only 8 non-white socks....and 10 possible colors...so 8/10

Answer 28

i must be one of the few question askers here who's actually doing the explaining...

Answer 29

you need to choose 1 white sock on one of the first 3 draws... that's the part that is throwing me.

if you choose 8 non-whites out of 10, 7 non-whites out of 9, ...

then your third term is "choose one of 2 white socks out of 8 remaining"

Got it (finally)

I think that's right.

Answer 30

wonderful

Answer 31

sorry it was taking me awhile :) thanks for the patience :)

Answer 32

it's part of the job

Answer 33

but seriously....i might be the only user who explains the solution to the questions i do not know how to solve to other people

Answer 34

well, if you thought my logic was ok, it appears your solution is good :)

Answer 35

Having good logic and rusty math skills isn't always a good combo for me :)