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April 18, 2014

April 18, 2014

Posted by **Chelsea** on Saturday, May 28, 2011 at 8:44pm.

a.) You know that at least one of Ashley's children is a boy. What is the conditional probability that she has two boys?

b.) You know that Brianna's older child is a boy. What is the conditional probability that she has two boys?

please help, if you can :)

- Statistics -
**Mgraph**, Sunday, May 29, 2011 at 11:11amThe formula of the conditional probability

P(X\Y)=P(XY)/P(Y)

a)Y="at least one is a boy"

Y=BB+BG+GB, P(Y)=3/4

X=BB

If X then Y => XY=X P(XY)=P(X)=1/4

P(X\Y)=(1/4)/(3/4)=1/3

b)Y="the older child is a boy"

Y=BB+BG, P(Y)=1/2

X=BB, XY=X, P(XY)=1/4

P(X/Y)=(1/4)/(1/2)=1/2

- Statistics -
**Mgraph**, Sunday, May 29, 2011 at 10:23pmThe formula of the conditional probability

P(X\Y)=P(XY)/P(Y)

a)Y="at least one is a boy"

Y=BB+BG+GB, P(Y)=3/4

X=BB

If X then Y => XY=X P(XY)=P(X)=1/4

P(X\Y)=(1/4)/(3/4)=1/3

b)Y="the older child is a boy"

Y=BB+BG, P(Y)=1/2

X=BB, XY=X, P(XY)=1/4

P(X/Y)=(1/4)/(1/2)=1/2

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