A delegation of 3 is selected from a city council made up of 4 liberals and 3 conservatives. What is the expected number of liberals in the delegation? Round to 2 decimal places, if necessary.
I know how to solve this problem, but the answer I keep coming up with is not correct. Please help?!
2006-06-27 15:58:37 · 10 answers · asked by Shorty 3 in Education & Reference ➔ Homework Help
Moron - I have been working on my homework for four and a half hours, and this is the only one to which I cannot get the correct answer.
2006-06-27 16:03:25 · update #1
Sorry tdw - that's not right either. Thanks, though. :(
2006-06-27 16:06:52 · update #2
2.33 sorry i'm not sure though
2006-06-27 16:09:21 · answer #1 · answered by Anonymous · 0⤊ 0⤋
We need some way of listing outcomes here. Basically, you are looking for an average.
It could be that you select 3 liberals. There are 4 ways of doing this.
It could be that you select 2 liberals and 1 conservative. There are 18 ways of doing this.
It could be that you select 1 liberal and 2 conservatives. There are 3 ways of doing this.
It could be that you select 3 conservatives. There is only 1 way to do this.
So there are 26 outcomes that we are dealing with. The result we seek is found by:
[(3 liberals)(4 ways) + (2 liberals)(18 ways) + (1 liberal)(3 ways) + (0 liberals)(1 way)]/26
= [(3)(4) + (2)(18) + (1)(3) + (0)(1)]/26
= [12 + 36 + 3 + 0]/26
= 51/26 = 1.96 liberals (rounded to 2 decimal places)
2006-06-27 16:05:02 · answer #2 · answered by tdw 4 · 0⤊ 0⤋
Hypergeometric distribution
r = # of liberals = 4
N = total # of candidates = 7
n = # in delegation = 3
x = # of liberals in delegation = ?
Expected value:
E[x] = n*r/N = 3*4/7 = 12/7 = 1.71
Since you can't have a part of a liberal, I would actually round the answer to 2.
2006-06-27 16:05:54 · answer #3 · answered by Anonymous · 0⤊ 0⤋
I'd guess it's most likely to be 2 liberals, because there can be no fraction of a person and liberals are greater in number than conservatives on the city council.
2006-06-27 16:08:21 · answer #4 · answered by anonymous 7 · 0⤊ 0⤋
I am not sure if this is correct, but try...
4 liberals / 7 total X 3. So the equation is 4/7 (3/1) = 1.71 liberals. Let me know if that is right.
2006-06-27 16:08:49 · answer #5 · answered by Just a Girl 3 · 0⤊ 0⤋
1.71.... just multiply the ratio of liberals (4/7) by the number of the people inthe delegation (3) and you get (12/7), which is 1.71 when rounded to two decimal places
P.S. next time do your own homework
2006-06-27 16:07:17 · answer #6 · answered by Christy P 2 · 0⤊ 0⤋
I love that some of you who answered this question are in the homework help section yet told her to do her own homework! It's not like those are the only questions she asks! Nice! Hehe
2006-06-27 16:23:06 · answer #7 · answered by ocgringa 2 · 0⤊ 0⤋
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2006-06-27 18:48:00 · answer #8 · answered by Anonymous · 0⤊ 0⤋
.1865
i guessed
2006-06-27 16:02:12 · answer #9 · answered by shorty 3 · 0⤊ 0⤋
do your own homework!!!
2006-06-27 16:01:36 · answer #10 · answered by That one guy 6 · 0⤊ 0⤋