a committee is to consist of 3 teachers and 3 parents, who are to be chosen from a group of 20 teachers and 100 parents. if half the teachers are female, and 80 parents are female, find the probability that the comittee has only female members

Question

amistre64 · Answer

3t and 3p ; from 20t and 100p....

amistre64 · Answer

the probability of 3/20 * 3/100 is a round about to the answer

amistre64 · Answer

since we are dealing with groups; we wanna use nCr if you can

anonymous · Answer

yeah that would probably work better

amistre64 · Answer

when a set has a number of same units;

          n!
--------------- gets you some answer
n1! n2! n3! ... nk!

amistre64 · Answer

lol .... i had this down the other day :)

amistre64 · Answer

table it...

amistre64 · Answer

$$
\begin{array}c
 &|&M&F&|&sum\
--&|&--&--&|&--\
T&|&10&10&|&20\
P&|&20&80&|&100\
--&|&--&--&|&--\
sums&|&30&90&|&120
\end{array}
$$

amistre64 · Answer

the probability of picking a female teacher is 10/120
the probability of picking a female parent is  80/120

agreed?

anonymous · Answer

correct

amistre64 · Answer

and to get 3f- teachers and 3 f-parents:

3(10/120) * 3(80/120)

am i right or wrong?

amistre64 · Answer

if im right; that .50

anonymous · Answer

i don't think so because if you pick a female teacher then you are going to have one less female and also one less out of the total
same with the parents

amistre64 · Answer

P( ft $\cap$ ft $\cap$ ft $\cap$ fp $\cap$ fp $\cap$ fp ) = 

ft*ft*ft*fp*fp*fp maybe?

amistre64 · Answer

good thinking;

anonymous · Answer

it has something with using nCr

amistre64 · Answer

10 .9 .8
-----------   perhaps the probability for 3 female teachers?
120.119.118

amistre64 · Answer

nCr is a shortcut somehow, just cant recall it :)

amistre64 · Answer

20c10 * 100c80;  or some such

amistre64 · Answer

we got any options to choose from?

amistre64 · Answer

80.79.78           10.9.8
----------- * ---------- = .000134...
120.119.118  117.116.115

amistre64 · Answer

this way feels right...

anonymous · Answer

how bout only 1 parent and only 1 teacher who are female?

amistre64 · Answer

10*80
--------  right?
120*119

amistre64 · Answer

.056 sound right?

anonymous · Answer

yikes just when i got used to calling you "master"

anonymous · Answer

now i have to say "yes, guru"?  doesn't have quite the same ring to it.

amistre64 · Answer

i know; i was hoping for some grander :)

amistre64 · Answer

... they call me MR Tibbs!!

anonymous · Answer

wondering if they just got rid of the title "master" or if you surpassed some other unknown mark

anonymous · Answer

i own that car!

amistre64 · Answer

surpassed the exp threshold

anonymous · Answer

in the movie rod steiger drives a belevedere.  i have one just like it.

amistre64 · Answer

:)