Mathematics: 49% of U.S. adults have very little confidence in newspapers. You randomly select 10 U.S. adults. Find the probability that the number of U.S. adults who have very little confidence in newspapers is (a) exactly five, (b) at least six, and (c) less than four.

49% of U.S. adults have very little confidence

Ответ:

meep26wesley

28.01.2022

Mathematics

a) P(x=5) = 0.2456

b) P(x≥6) = 0.3526

c) P(x<4) = 0.1887

Step-by-step explanation:

We can model this as a binomial experiment, with sample size n=10 and p=0.49.

To calculate the probability of having k subjects with very little confidence in the sample of 10, we solve:

$P(x=k) = \dbinom{n}{k} p^{k}q^{n-k}$

a) We have to calculate P(x=5).

For a binomial variable with n=10 and p=0.49, this can be calculated as:

$P(x=5) = \dbinom{10}{5} p^{5}q^{5}=252*0.0282*0.0345=0.2456\\\\$

b) We have to calculate P(x≥6). This can be calculated as:

$P(x\geq6)=P(x=6)+P(x=7)+P(x=8)+P(x=9)+P(x=10)\\\\\\P(x=6) = \binom{10}{6} p^{6}q^{4}=210*0.0138*0.0677=0.1966\\\\P(x=7) = \binom{10}{7} p^{7}q^{3}=120*0.0068*0.1327=0.1080\\\\P(x=8) = \binom{10}{8} p^{8}q^{2}=45*0.0033*0.2601=0.0389\\\\P(x=9) = \binom{10}{9} p^{9}q^{1}=10*0.0016*0.51=0.0083\\\\P(x=10) = \binom{10}{10} p^{10}q^{0}=1*0.0008*1=0.0008\\\\\\P(x\geq6)=0.1966+0.1080+0.0389+0.0083+0.0008\\\\P(x\geq6)=0.3526$

c) We have to calculate P(x<4). That is:

P(x

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49% of U.S. adults have very little confidence in newspapers. You randomly select 10 U.S. adults. Find the probability that the number of U.S. adults who have very little confidence in newspapers is (a) exactly five, (b) at least six, and (c) less than four.

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