Question

Assume that when adults with smartphones are randomly​ selected,

46​%

use them in meetings or classes. If

7

adult smartphone users are randomly​ selected, find the probability that at least

2

of them use their smartphones in meetings or classes.

Answer 1

Ans: $n=7$ , probability that a adult use a smartphone in meeting or classes: $P=0.46$   

X is the number of adults who use a smartphone in meeting or classes,

Then,

$P(X= x)=\binom{n}{x}P^{x}(1-P)^{n-x}$

The probability that at least 2 of them use their smartphones in meetings or classes is:

Here  $P(X\geqslant 2)=1-P(X<2)=1-[P(X=0)+P(X=1)]$

  $=1-[\binom{7}{0}(0.46)^{0}(0.54)^{7}+\binom{7}{1}(0.46)^{1}(0.54)^{6}]$

=0.9067