Question 1155751
<pre>
There are 16 cases of a family with 4 children, (no twins)
We eliminate by lining through, the ones that are not given.
So that leaves 14.

First   Second    Third   Youngest    Given?   Success?
Born     Born      Born
<s>  B        B         B        B        No</s>        
  B        B         B        G        Yes        No
  B        B         G        B        Yes        No
  B        B         G        G        Yes        No
  B        G         B        B        Yes        No
  B        G         B        G        Yes        No
  B        G         G        B        Yes        No
  B        G         G        G        Yes        No
  G        B         B        B        Yes        Yes
  G        B         B        G        Yes        Yes        
  G        B         G        B        Yes        Yes
  G        B         G        G        Yes        Yes
  G        G         B        B        Yes        Yes
  G        G         B        G        Yes        Yes
  G        G         G        B        Yes        Yes
  <s>G        G         G        G        No</s> 

So that's 7 successes out of 14, so the probability is 7/14 which
reduces to 1/2.

Edwin</pre>