Question

Assume that when adults with smartphones are randomly​ selected, 57​% use them in meetings or classes. If 30 adult smartphone users are randomly​ selected, find the probability that exactly 23 of them use their smartphones in meetings or classes.

Answer 1

The probability that randomly selected adult uses smartphone in meetings is p=0.57 and the probability that randomly selected adult doesn't use smartphone in meetings is q=1-p=1-0.57=0.43.

The probability that exactly 23 of 30 use their smartphones in meetings is

`Pr=C_(30)^(23)p^(23)q^(30-23)=(30!)/(23!(30-23)!)\cdot (0.57)^(23)\cdot (0.43)^7=2,035,800\cdot (0.57)^(23)\cdot (0.43)^7\approx 0.013432.`