In a poll conducted by a survey firm, 82% of respondents said that their jobs were sometimes or always stressful. Eleven workers are chosen at random for the Binomial experiment. What is the probability that more than 9 of them find their jobs stressful

Respuesta :

Answer:

[tex] P(X >9) = P(X=10) +P(X=11) [/tex]

And we can find the individual probabilities with the mas function adn we got:

[tex]P(X=10)=(11C10)(0.82)^{10} (1-0.82)^{11-10}=0.272[/tex]  

[tex]P(X=11)=(11C11)(0.82)^{11} (1-0.82)^{11-11}=0.113[/tex]  

And replacing we got:

[tex] P(X>9) =0.272 +0.113= 0.385[/tex]

Step-by-step explanation:

Let X the random variable of interest "number of workers who find their jobs stressful", on this case we now that:  

[tex]X \sim Binom(n=11, p=0.82)[/tex]  

The probability mass function for the Binomial distribution is given as:  

[tex]P(X)=(nCx)(p)^x (1-p)^{n-x}[/tex]  

Where (nCx) means combinatory and it's given by this formula:  

[tex]nCx=\frac{n!}{(n-x)! x!}[/tex]  

We want to find the following probability:

[tex] P(X >9) = P(X=10) +P(X=11) [/tex]

And we can find the individual probabilities with the mas function adn we got:

[tex]P(X=10)=(11C10)(0.82)^{10} (1-0.82)^{11-10}=0.272[/tex]  

[tex]P(X=11)=(11C11)(0.82)^{11} (1-0.82)^{11-11}=0.113[/tex]  

And replacing we got:

[tex] P(X>9) =0.272 +0.113= 0.385[/tex]