Answer: Our required probability is 0.167.
Step-by-step explanation:
Since we have given that
n = 15
Probability of success p = 80% = 0.8
Probability of failure q = 20% = 0.2
We need to find the probability that at least fourteen will work.
So, by Binomial distribution, we get that
[tex]P(X\geq 14)=P(X=14)+P(X=15)\\\\P(X\geq 14)=^{15}C_{14}(0.8)^{14}(0.2)+^{15}C_{15}(0.8)^{15}\\\\P(X\geq 14)=0.167[/tex]
Hence, our required probability is 0.167.