Question

Assume that when adults with smartphones are randomly​ selected, 43​%use them in meetings or classes. If 15 adult smartphone users are randomly​ selected, find the probability that exactly 12 of them use their smartphones in meetings or classes.

Answer 1

p = probability of success = 0.43 ( we converted 43% in to decimal )

n = sample size = 15

We are asked to find

P ( X = 12 )    [ exactly 12 of then use theiir smarthphones in meetings or classes that means = 12 ]

We use formula of binomial distribution.

We plug the value of n , x and p

! : factorial sign

So above formula becomes

Final answer :-

Probability that exactly 12 of them use their smartphones in meetings or classes = 0.003367111

Note : you can use excel to find the direct answer

Select empty box from excel and type

=BINOMDIST(12,15,0.43,0)

And press enter you get the same answer 0.003367111