Question 1134979:  Assume that when adults with smartphones are randomly selected, 42% use them 
in meetings or classes. If 8 adult smartphone users are randomly selected, 
find the probability that at least 5 of them use their smartphones in 
meetings or classes. 
 Answer by AnlytcPhil(1810)      (Show Source): 
You can  put this solution on YOUR website! Assume that when adults with smartphones are randomly selected, 42% use them 
in meetings or classes. If 8 adult smartphone users are randomly selected, 
find the probability that at least 5 of them use their smartphones in 
meetings or classes.
Got a TI-83 or 84?
On those calculators binomcdf( calculates for n trials, the probability that
there will be a certain number or fewer successes.  Since this is a "5 or
more" problem, we have to find the probability of the complement event "4 or
fewer", and subtract it from 1.
The complement event of 
"at least 5 of the 8 use their smartphones in meetings or classes" 
is 
"4 or fewer of the 8 use their smartphones in meetings or classes."
So type in "1-" on the main screen so that what we get will be subtracted from 1.
You'll find binomcdf( by pressing 2ND then VARS and scrolling down to it.
That's 8 trials, p: is 0.42, and the x-value is 4,  you should make sure
that you see this on your screen:
1-binomcdf(8,0.42,4)
then press ENTER.
Answer: 0.206164373
Edwin  
 
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