Answer :
Answer:
[tex]P(X=5)=(7C5)(0.53)^5 (1-0.53)^{7-5}=0.194[/tex]
Then the probability that exactly 5 of them use their smartphones in meetings or classes is 0.194
Step-by-step explanation:
Let X the random variable of interest "number of adults with smartphones", on this case we now that:
[tex]X \sim Binom(n=7, p=0.53)[/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]
And we want to find this probability:
[tex] P(X=5)[/tex]
Using the probability mass function we got:
[tex]P(X=5)=(7C5)(0.53)^5 (1-0.53)^{7-5}=0.194[/tex]
Then the probability that exactly 5 of them use their smartphones in meetings or classes is 0.194