Respuesta :
A - at leats one is a girl
B - none is a girl
[tex] |\Omega|=2^4=16\\
|B|=1\\
|A|=|\Omega|-|B|=16-1=15\\\\
P(A)=\dfrac{15}{16}\approx94\% [/tex]
This is a case of binomial probability, with n=4 and p=0.5.
Note that P(at least one of the four children is a girl) = 1 - P(no girls among 4 children).
P(no girls among 4 children) = binompdf(4,0.5,0) = 0.0625
Then P(at least one of the four children is a girl) = 1 - 0.0625 = 0.94.