In a certain? country, the true probability of a baby being a girlgirl is 0.4640.464. among the next fivefive randomly selected births in the? country, what is the probability that at least one of them is a boyboy??

Respuesta :

This is a binomial probability:

ⁿCₓ(p)ˣ(q)ⁿ⁻ˣ

P(girls) = 0.464 ; P(NO girls) = 1-0.464 = 0.536
Then:
p(girls) = 0.464
q(NO girls) = 0.536
n = 5
Probability(NO GIRLS) = ⁵C₀(0.464)⁰(0.536)⁵⁻⁰
⁵C₀ = 1; (0.464)⁰ = 1

Probability(NO GIRLS) = (0.536)⁵
Probability(NO GIRLS) = 0.04424

Probability(at LEAST one boy) = 1 - 0.04424 = 0.955