SOLUTION: Assume that when adults with smartphones are randomly​ selected, 55​% use them in meetings or classes. If 7 adult smartphone users are randomly​ selected, find the probabili

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Question 1167372: Assume that when adults with smartphones are randomly​ selected, 55​% use them in meetings or classes. If 7 adult smartphone users are randomly​ selected, find the probability that at least 4 of them use their smartphones in meetings or classes.
Answer by Boreal(15235)   (Show Source): You can put this solution on YOUR website!
This is a binomial with n=7 p=0.55
a least 4 of them use their smartphones
that is 1-prob(3) of them use them.
=0.6083 is answer.
probability 4 use them is 7C4*0.55^4*0.45^3=0.2918
for 5 it is 0.2140
for 6 it is 0.0872
for 7 it is 0.55^7 or 0.0152
add them to get 0.6082 (rounding error)

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