Question 1167362: Assume that when adults with smartphones are randomly selected, 52% use them in meetings or classes. If 11 adult smartphone users are randomly selected, find the probability that fewer than 5
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=11 p=0.52 and want 0 to 4.
Can do this by doing each calculation from 0 to 4 (e.g.,for p(4) it is 11C4*0.52^4*0.48^7) (=0.1416) p(0) 0.48^11=0.0003
or
binomcdf(11,0.52,4)=0.2312
mean is 5.72 and variance is 2.76 (so sd 1.66), so approximately less than 1.22/1.66 sd and that gives a probability of 0.2327, so rough approximation a very reasonable check.
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