Answer: 0.9617
Step-by-step explanation:
Given : The proportion of adults use their phones in meetings or classes : p=0.57
Number of adults randomly selected : n= 9
Let x be the random variable that represents the number of adults use their phones in meetings or classes.
By using binomial probability formula, to find the probability of getting success in x trials.
[tex]P(x)=^nC_xp^x(1-p)^{n-x}[/tex]
The probability that at least 3 of them use their smartphones in meetings or classes will be :-
[tex]P(x\geq3)=1-P(x<3)\\\\=1-(P(0)+P(1)+P(2))\\\\=1-(^9C_0(0.57)^0(0.43)^9+^9C_1(0.57)^1(0.43)^8)\\\\=1-((0.43)^9+(9)(0.57)^1(0.43)^8+(36)(0.57)^2(0.43)^7)\\\\=0.961708368616\approx0.9617[/tex]
Hence, the required probability is 0.9617 .
