This is why I've never finished an IQ test. I get impatient and frustrated with how none of the situations ever make any sense. It's the "one train leaves Boston at 3:45 traveling at 90 miles per hour..." problem all over again. It's a problem that will never happen and the solution of which I can't use practically. Why can't the father stay with the daughters?
Here's the real-world solution: the policeman handcuffs and subdues the criminal and he tells the father to ferry his family across the river one at a time, to leave the wife on the shore with him until he gets to her, and to not give him any BS about one family member not wanting to ride with another. And since there's one left over, the father grows a pair and swims the river like a boss, leaving the raft for the policeman and the criminal. Or the policemen handcuffs the criminal to a pole or something and radios to his buddies to pick up the thief when he gets to the other side.
That gets me an F in school but an A in practical living.