Question 850808
Look at all possible outcomes, then count the number of females.
MMMM=0
MMMF=1
MMFM=1
MMFF=2
MFMM=1
MFMF=2
MFFM=2
MFFF=3
FMMM=1
FMMF=2
FMFM=2
FMFF=3
FFMM=2
FFMF=3
FFFM=3
FFFF=4
So then the discrete probability distribution looks like,
0,1/16
1,4/16
2,6/16
3,4/16
4,1/16
{{{m=sum(x*p(x))=(0*1+1*4+2*6+3*4+4*1)/16=32/16=2}}}
{{{Var=sum((x-m)^2*p(x))=((0-2)^2*1+(1-2)^2*4+(2-2)^2*6+(3-2)^2*4+(4-2)^2*1)/16=(4+4+0+4+4)/16=16/16=1}}}
{{{sigma=sqrt(Var)=1}}}