There is a 90% chance that a registered voter in Burghtwon

Question

There is a 90% chance that a registered voter in Burghtwon voted in the last election. If five registered voters are chosen at random, what is the approximate likelihood that exactly four of them voted in the last election?

a) 26.2 %
b) 32.8%
c) 43.7 %
d) 59.0 %
e) 65.6%

HIMALAYA · Answer

=5c4 (0.9)^4(0.1)

conocieur · Answer

same as Himalaya use binomial

ACB P^(B)*Q(A-B)

joemama142000 · Answer

thanks guys, however i don't understand the equation that you guys used. Where did it come from and when do you use such an equation?

What is ACB?
and 5c4?

conocieur · Answer

sorry about my notation it is certainly pretty lame

AcB means combinations, so A! / B! (A-B)!

p the probability of ocurrence and q would be (1-p)

marth750 · Answer

Answer is B.
--

1. Find combined probability of 4 out of 5 voters:
9/10 + 9/10 + 9/10 + 9/10 + 1/10 = 9^4/10^5

2. Find # of combinations when 4 out of 5 voters:
(5*4*3*2*1)/(4*3*2*1) = 5

3. Multiply # of Comb. by Probability:
5 * (9^4/10^5) = 32.8%

There is a 90% chance that a registered voter in Burghtwon

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