Answer :
Using the binomial distribution, the probabilities are given as follows:
a) 0.0747 = 7.47%.
b) 0.8725 = 87.25%.
c) 0.1256 = 12.56%.
What is the binomial distribution formula?
The formula is:
[tex]P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}[/tex]
[tex]C_{n,x} = \frac{n!}{x!(n-x)!}[/tex]
The parameters are:
- x is the number of successes.
- n is the number of trials.
- p is the probability of a success on a single trial.
The values of the parameters are:
n = 20, p = 0.6.
Item a:
The probability is P(X = 15), hence:
[tex]P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}[/tex]
[tex]P(X = 15) = C_{20,15}.(0.6)^{15}.(0.4)^{5} = 0.0747[/tex]
Item b:
The probability is:
[tex]P(X \geq 10) = P(X = 10) + P(X = 11) + P(X = 12) + \cdots + P(X = 20)[/tex]
Finding each value with the equation we used in item a, we have that:
[tex]P(X \geq 10) = 0.8725[/tex]
Item c:
At least 20 - 5 = 15 on the road, hence the probability is:
[tex]P(X \geq 15) = P(X = 15) + P(X = 16) + \cdots + P(X = 20)[/tex]
Then, using the same procedure as item b, we have that:
[tex]P(X \geq 15) = 0.1256[/tex]
More can be learned about the binomial distribution at https://brainly.com/question/24863377
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