In: Math
Assume that when adults with smartphones are randomly selected, 49% use them in meetings or classes. If 15 adult smartphone users are randomly selected, find the probability that exactly 11 of them use their smartphones in meetings or classes.
According to the given question , the adults with smartphones are randomly selected, 49% use them in meetings or classes. Therefore the probability of the adults smartphones in meetings or classes is
.
It is follow binomial distribution , where 
 is defined as  the adults smartphones in meetings or
classes and the probability mass function of binomial distribution
(discreate distribution) is defined as:
where 
If 
 adult smartphone users are randomly selected, then the
probability that exactly 
 of them use their smartphones in meetings or classes is determined
as:


  

Therefore if 15 adult smartphone users are randomly selected, then the probability that exactly 11 of them use their smartphones in meetings or classes is
