Answer: 0.5
Step-by-step explanation:
Binomial probability formula :-
[tex]P(x)=^nC_x\ p^x(q)^{n-x}[/tex], where P(x) is the probability of getting success in x trials , n is the total trials and p is the probability of getting success in each trial.
Given : The probability that the adults follow more than one game = 0.30
Then , q= 1-p = 1-0.30=0.70
The number of adults surveyed : n= 15
Let X be represents the adults who follow more than one sport.
Then , the probability that fewer than 4 of them will say that football is their favorite sport,
[tex]P(X\leq4)=P(x=0)+P(x=1)+P(x=2)+P(x=3)+P(x=4)\\\\=^{15}C_{0}\ (0.30)^0(0.70)^{15}+^{15}C_{1}\ (0.30)^1(0.70)^{14}+^{15}C_{2}\ (0.30)^2(0.70)^{13}+^{15}C_{3}\ (0.30)^3(0.70)^{12}+^{15}C_{4}\ (0.30)^4(0.70)^{11}\\\\=(0.30)^0(0.70)^{15}+15(0.30)^1(0.70)^{14}+105(0.30)^2(0.70)^{13}+455(0.30)^3(0.70)^{12}+1365(0.30)^4(0.70)^{11}\\\\=0.515491059227\approx0.5[/tex]
Hence, the probability rounded to the nearest tenth that fewer than 4 of them will say that football is their favorite sport =0.5
