Thirteen (13) children, in three separate locations, are in a crisis.  You have the means and opportunity to intercede and potentially save at least one (1) child.  At the first location are ten (10) children who belong to your neighbor, a life-long friend.  In the second location are your own child and your niece or nephew.  And in the final location is the child of a person whom you have never met before:

If you attempt to save your neighbors children you will save all 10 if you succeed, but you have less than a 10% chance of success, and any attempt to save them results in the death of the other 3 children.

If you attempt to save your child or your relative's child you will have a 100% chance of saving the one you choose, but the other child has only a 10% chance of survival, and this choice will result in the death of the other 11 children.

If you choose to save the stranger's child you will have a 100% chance of success, however this will result in the death of all other children.

Finally if you take no action at all your neighbors children and the stranger's child will all survive, however one of the children at location two (your child and your niece/nephew) will die and the other has only a 50% chance of survival.  You do not know, and cannot choose, which child receives which fate.