Answer:
Probability that more than eight but fewer than 12 of the 20 constituents sampled believe their representative possesses low ethical standards is 0.417890.
Step-by-step explanation:
We are given that the paper claims that 43% of all constituents believe their representative possesses low ethical standards.
Suppose 20 of a representative's constituents are randomly and independently sampled.
The above situation can be represented through binomial distribution;
[tex]P(X=r) = \binom{n}{r} \times p^{r} \times (1-p)^{n-r} ; x = 0,1,2,3,.....[/tex]
where, n = number of trials (samples) taken = 20 constituents
r = number of success = more than eight but fewer than 12
p = probability of success which in our question is probability that
all constituents believe their representative possesses low
ethical standards, i.e; p = 43%
Let X = Number of constituents who believe their representative possesses low ethical standards
So, X ~ Binom(n = 20 , p = 0.43)
Now, Probability that more than eight but fewer than 12 of the 20 constituents sampled believe their representative possesses low ethical standards is given by = P(8 < X < 12)
P(8 < X < 12) = P(X = 9) + P(X = 10) + P(X = 11)
= [tex]\binom{20}{9} \times 0.43^{9} \times (1-0.43)^{20-9}+ \binom{20}{10} \times 0.43^{10} \times (1-0.43)^{20-10}+\binom{20}{11} \times 0.43^{11} \times (1-0.43)^{20-11}[/tex]
= [tex]167960 \times 0.43^{9} \times 0.57^{11}+ 184756 \times 0.43^{10} \times 0.57^{10}+167960 \times 0.43^{11} \times 0.57^{9}[/tex]
= 0.417890
Hence, the required probability is 0.417890.
The probability that more than eight but fewer than 12 of the 20 constituents sampled believe their representative possesses low ethical standards is; C. 0.417890
We are given;
proportion; p = 43% = 0.43
sample size; n = 20
P(X = x) = ⁿCₓ * pˣ * (1 - p)ⁿ ⁻ ˣ
Thus the probability that more than eight but fewer than 12 of the 20 constituents sampled believe their representative possesses low ethical standards is;
P(8 < X < 12) = P(X = 9) + P(X = 10) + P(X = 11)
From online binomial probability calculator, we have;
P(8 < X < 12) = 0.17419889 + 0.14455452 + 0.09913627
P(8 < X < 12) = 0.417890
Read more about binomial probability at; https://brainly.com/question/15246027
